Сборник задач по высшей математике 2 том
.pdf7.4.3. |
HaihH p83JIO:>KeHHe <PyHKI.J;HH |
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B PH,n: JIopaHa B oco6oit |
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z(3 -z) |
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TOqKe Zo = O. YKa3aTb rJIaBHYIO H rrpaBHJIbHYIO qacTH pH,n:a H em 06JIaCTb CXO,n:HMOCTH.
a IIpe,n:BapHTeJIbHo rrpe,n:CTaBHM ,n:aHHYIO ,n:p06b B BH,n:e CYMMbI ,n:BYX rrpa-
cTeitwHx ,n:po6eit
2 _A+-.lL
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z(3-z) - z |
3-z' |
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Hait,n:eM qHCJIa A H B: |
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2 |
A(3 - |
z) + Bz |
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z(3 - z) |
z(3 - z) |
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CJIe,n:OBaTeJIbHO, o· z + 2 = (B - A)z + 3A, oTKy,n:a |
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{o= B - A, |
T. e. |
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A = B = -3 • |
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2=3A, |
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2 |
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2/3 |
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IITaK, ( |
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= - z + -3-' |
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z3-z |
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- z |
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2/3 |
Y:>Ke rrpe,n:CTaBJIeHa B BH,n:e CYMMbI (CocToHw;eit H3 |
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TaK KaK ,n:p06b --:z- |
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o,n:Horo CJIaraeMoro) qJIeHOB BH,n:a cnzn , TO OCTaeTCH HaitTH pa3JIO:>KeHHe ,n:po-
2/3 |
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(4.4) |
(B Kpyre Iz I < 1) H |
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6H 3 _ z· ,I1;JIH ::noro BOCrrOJIb3yeMcH pa3JIO:>KeHHeM |
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rrOJIyqHM: |
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32~3z ~ 3 ( :~f) ~ /3 ( 1 + j + mz + ... + (jr+.) ~ |
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+ ... |
= 32 |
+ 33 Z + 34 Z |
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+ ... + 3n +2 z |
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8TOT pH,n: (6eCKOHeqHO y6bIBaIOW;M reOMeTpHqeCKaH rrporpeccHH) CXO,n:HTCH rrpH Iql = I~I < 1, T.e.B OTKPbITOM Kpyre I~I < 1, HJIH Izl < 3.
Terrepb 3arrHweM PH,n: JIopaHa ,n:JIH HCXO,n:HOit ,n:p06H:
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2/3 2 |
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z(3 - |
z) = --:z- + 32 |
+ 33z + 34z |
+ ... = n~l 3n +2z . |
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06JIacTb CXO,n:HMOCTH 9Toro pH,n:a - |
KOJIbI.J;O 0 < Izl < 3. IIepBoe CJIaraeMOe, |
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2/3 |
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rrpaBHJIb- |
--:z-, HBJIHeTCH rJIaBHoit qaCTbIO pH,n:a, OCTaBWMCH qacTb pH,n:a - |
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HOit. |
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7.4.4. |
HaitTH pa3JIO:>KeHHe <PyHKI.J;HH |
(2 |
) B PH,n: JIopaHa B oKpecTHa- |
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z3-z |
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CTH 6eCKOHeqHO y,n:aJIeHHoit TOqKH. YKa3aTb rJIaBHYIO H rrpaBHJIbHyIO qacTH pH,n:a Hero 06JIaCTb CXO,n:HMOCTH.
470
a 'MbIY)Ke 3HaeM (3a,l1,aqa 7.4.3), QTO |
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2/3 |
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z(3 _ z) = ----z + 3 _ z' 3arrHmeM |
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pa3JIO)KeHHe <PYHKIJ,HH |
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B 6ecKOHeQHO y6bIBaIOIIIyIO reOMeTpHQeCKYIO |
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-3- |
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-z |
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«BCJIHKO», T. e. l- «MaJIO»: |
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rrporpeCCHIO B 06JIacTH, B KOTOPOil: z - |
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2/3 |
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2/3 |
3) |
= |
2 |
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3 |
(3)2 |
(3)n - l) |
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3-z |
-z |
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- 3z |
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1+ z + z |
+ ... + z |
+ ... = |
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(1- z |
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2 |
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2·3 |
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= -------- |
zn |
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3z |
Z2 |
z3 |
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OTOT p.H,l1, CXO,l1,HTC.H rrpH |
I~I< 1, T. e. B 06JIacTH Izl > 3. |
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Terrepb 3arrHmeM pa3JIO)KeHHe B p.H,l1, JIopaHa ,l1,JI.H HCXO,l1,HOil: ,l1,P06H:
2 z(3 - z)
06JIacTb CXO,l1,HMOCTH :;noro p.H,l1,a - KOJIblJ,O Izl |
> 3. |
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HaiJ.mu pa3,//,(X)/CeHue tfiYH'II:'qUU 6 pSla JIopaHa 6 mO"l,'II:e Zo no cmene'H.SI.M z - ZOo Y'II:a3am'b Z.lta6HY'IO U npa6U.It'bHY'IO "I,acmu pSlaa U ezo o6.1tacm'b CXOaUMocmu.
7.4.5. |
1 |
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z cosz, |
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Zo = 00. |
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7.4.6. |
a) Zo = 0; |
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z sirr z, |
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a) Zo = 0; |
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Zo = 00. |
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1 |
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7.4.7. |
ez + 1, |
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a) Zo = -1; |
6) |
Zo = 00. |
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3z +4 |
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7.4.S. |
e z+ 1 , |
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a) Zo = -1; |
6) |
Zo = 00. |
7.4.9.sin(2 + z),
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a) Zo = 0; |
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Zo = 00. |
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7.4.10. |
3z + 10 |
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cos z + 3 'Zo = -3. |
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7.4.11. |
2 |
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z -1' |
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Zo = 00. |
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a) Zo = 1; |
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7.4.12. |
3 + 2i |
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(z+i)2' |
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a) Zo = -i; |
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Zo = 00. |
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7.4.13. |
~,zo=1. |
7.4.14. |
Z + 2i |
2' Zo = 1. |
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(Z - 1) |
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z - |
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7.4.15. |
1 |
= 1. |
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Z' Zo |
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7.4.16. |
2 |
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z +i' |
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a) Zo = 0; |
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6) Zo = 00. |
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7.4.17. |
z2 |
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7.4.18. |
z+2 |
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--1' Zo =-1. |
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--3' Zo = 1. |
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z- |
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z- |
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7.4.19. |
z-2 |
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(z - 1)(z + 2)' |
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6) Zo = -2. |
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a) Zo = 1; |
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7.4.20. |
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= 1. |
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z-2 |
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(z - 1)(z + 2)' Zo |
7.4.21. |
(z-1 )( z+2)' Zo =-1. |
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7.4.22. |
HaiiTH Bce oc06ble TO'iKH<PYHKIIHH |
.-l2 H Ollpe,Il;eJIHTb HX THII, |
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,Il;JI.H 1I0JIloca HaiiTH ero 1I0P.H,Il;OK. |
z- |
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a OC06bIMH TO'iKaMH<PYHKIIHH .HBJI.HIOTC.H TO'iKHZ1 = 2 H Z2 = 00. |
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Cnoco61. |
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= 0, TO lim.-l2 |
= 00, 3Ha'iHT,TO'iKaZ1 |
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a) TaK KaK |
lim (z - |
2) |
2 |
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z--+2 |
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z--+2 Z - |
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.HBJI.HeTC.H 1I0JIIOCOM. |
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Ollpe,Il;eJIHM 1I0P.H,Il;OK 9Toro 1I0JIIOCa, )J;JI.H 'ieroHaii,Il;eM IIpe,Il;eJI |
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lim J(z) . (z - |
2)1 = lim z - 22 = lim 1 = 1 t= O. |
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z--+2 |
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z--+2 Z - |
z--+2 |
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3Ha'iHT,1I0P.H,Il;OK 1I0JIIOCa paBeH 1. |
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6) TaK KaK |
lim .-l2 |
= 0, TO TO'iKaZ2 |
= 00 |
.HBJI.HeTC.H YCTpaHHMoii |
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z--+oo z - |
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oc060ii TO'iKOii. |
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~:~~~!~<PYHKIIHIO J(z) = .-l2 B p.H,Il; JIopaHa 110 CTelleH.HM (z - |
2): |
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z- |
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.-l2 = |
1 . (z |
- 2)-1 - |
9TO H |
eCTb pa3JIO)KeHHe |
(COCTO.HlIIee |
H3 O,Il;HOrO |
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z- |
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- 2), |
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CJIaraeMoro) B p.H,Il; JIopaHa 110 CTelleH.HM (z |
CXO)J;.HlIIeeC.H |
B 06JIacTH |
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o< Iz - |
21 < +00. |
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a) TaK KaK 9TO pa3JIO)KeHHe CO,Il;ep)KHT KOHe'iHOe'iHCJIOCJIaraeMblX (a HMeHHO, O,Il;HO CJIaraeMoe) C OTpHIIaTeJIbHbIMH CTelleH.HMH (z - 2), TO TO'iKa
Z1 = 2 .HBJI.HeTC.H 1I0JIIOCOM. TaK KaK HaH60JIblIIM CTelleHb CJIaraeMblX BH,Il;a
B pa3JIO)KeHHH paBHa 1, TO 1I0P.H,Il;OK 1I0JIIOCa paBeH 1.
6) IIoCKOJIbKY pa3JIO)KeHHe <PYHKIIHH B p.H,Il; JIopaHa 110 CTelleH.HM (z - 2),
CXO)J;.HlIIeeC.H B OKpeCTHOCTH TO'iKHZ2 |
= 00, He CO,Il;ep)KHT 1I0JIO)KHTeJIb~bIX |
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CTelleHeii |
BH,Il;a (z - 2)n, TO TO'iKaZ2 |
.HBJI.HeTC.H YCTpaHHMoii oc060ii TO'i- |
Koii. |
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7.4.23. |
HaiiTH Bce oc06ble TO'iKH<PYHKIIHH |
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z+2
(Z2 - 4)(z - 2)2
H Ollpe,Il;eJIHTb HX THII, )J;JI.H 1I0JIIOCa HaiiTH ero 1I0P.H,Il;OK.
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o TaK KaK |
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z+2 |
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z+2 |
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z+2 |
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(Z2 - |
4)(z - 2)2 |
(z + 2)(z - |
2)(z - |
2)2 - |
(z + 2)(z - |
2)3' |
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TO OC06bIMH TOqKaMH <PYHKIJ;HH .HBJUIIOTC.H TOqKH Zl |
= -2, Z2 = 2, Z3 = 00. |
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a) IIoCKOJlbKY cYlllecTByeT KOHeqHbIii rrpe,l1.eJl |
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· |
z + 2 |
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1· |
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1 |
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1 |
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= 1m |
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1m |
+ 2)(z - |
2)3 |
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z--+( -2) (z |
z--+( -2) (z - 2)3 |
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TO TOqKa Zl = -2 .HBJl.HeTC.H YCTpaHHMoii oco6oii TOqKOii. |
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6) TaK KaK lim |
(z - |
2) = 0, TO |
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z--+( -2) |
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1· |
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z + 2 |
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1· |
1 |
= 00. |
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1m |
(z + 2)(z - |
= 1m |
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z--+2 |
2)3 |
z--+2 (z - 2)3 |
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CJle,l1.0BaTeJlbHO, TOqKa Z2 = 2 .HBJl.HeTC.H rrOJlIOCOM. |
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Orrpe,l1.eJlHM rrOp.H,l1.0K 3TOro rrOJllOca. OqeBH,l1.HO, |
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lim J(z) . (z - |
2)3 = lim |
1 |
3· (z - 2)3 = lim 1 = 1 ¥- 0. |
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z--+2 |
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z--+2 |
(z - |
2) |
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z--+2 |
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TaKHM o6pa30M, TOqKa Z2 = 2 .HBJl.HeTC.H rrOJlIOCOM 3-1'0rrOp.H,l1.Ka. |
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B) B CHJlY Toro, 'ITO |
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lim |
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z + 2 |
2)3 |
= lim |
1 |
= 0, |
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z--+oo (z + 2)(z - |
z--+oo |
(z - 2)3 |
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TOqKa Z3 = 00 .HBJl.HeTC.H YCTpaHHMoii oco6oii TOqKOii. |
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7.4.24. HaiiTH Bce oco6bIe TOqKH <PYHKIJ;HH sin ~2 H orrpe,l1.eJlHTb HX THrr, |
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z- |
a |
,l1.Jl.H rrOJlIOCa HaiiTH ero rrOp.H,l1.0K. |
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OC06bIMH TOqKaMH <PYHKIJ;HH .HBJl.HIOTC.H TOqKH Zl = 2 H Z2 = 00. |
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Cnoco61. |
2) = 0, TO lim ~2 = 00, H 3HaqHT, |
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a) TaK KaK lim (z - |
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z--+2 |
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z--+2 Z - |
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lim (sin~2) |
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z--+2 |
z - |
He cYlllecTByeT. OTCIO,l1.a CJle,l1.JeT, 'ITOTOqKa Zl = 2 .HBJl.HeTC.H cYlllecTBeHHo |
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co6oii TOqKOii. |
~2 = 0, TO |
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6) IIoCKOJlbKY lim |
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z--+oo Z - |
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lim (sin ~2) = 0, |
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z--+oo |
Z - |
CJle,l1.0BaTeJlbHO, TOqKa Z2 = 00 .HBJl.HeTC.H YCTpaHHMoii oco6oii TOqKOii.
Cnoco62.
Pa3JlO:>KHM <PYHKIJ;HIO J(z) = sin ~2 B p.H,l1. JIopaHa rro CTerreH.HM (z-2):
z-
sin _1_ |
= _1__ .1. |
1 |
+.1. |
1 |
+...+ (_l)n . |
1 |
+... |
z - 2 |
z - 2 3! |
(z - 2)3 |
5! |
(z - 2)5 |
(2n + I)! (z - |
2)2nH |
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06JlacTb CXO,l1.HMOCTH 9Toro p.H,l1.a - |
KOJlbIJ;O °< Iz - 21 < +00. |
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473
a) IIoJIY'IeHHoepa3JIO)KeHHe, CXOMrn;eeCfl B rrpOKOJIOTOii OKpeCTHOCTH TO'lKHZl = 2, COAep)KHT 6eCKOHe'lHoe'IHCJIOCJIaraeMhlX C OTpHlIaTeJIhHhIMH CTerreHflMH (z - 2), rr09TOMY TO'lKaZl flBJIfleTCfl cyrn;ecTBeHHO oco6oii TO'lKOii.
6) TaK KaK 9TO pa3JIO)KeHHe, CXOMrn;eeCfl B OKpeCTHOCTH TO'lKHZ2
He COAep)KHT CJIaraeMhIX C rrOJIO)KHTeJIhHhIMH CTerreHflMH (Z - 2), TO TO'lKa
Z2 flBJIfleTCfl YCTpaHHMoii oco6oii TO'lKOii. |
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7.4.25. HaiiTH Bce oco6hle TO'lKH<PYHKlIHH |
CO~Z |
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H orrpeAeJIHTh HX THrr, |
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AJIfl rrOJIIOCa HaiiTH ero rropflAOK. |
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a OC06hIMH TO'lKaMH<PYHKlIHH flBJIflIOTCfl Bce TO'lKH,B KOTOPhIX cos Z = 0, |
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T. e. TO'lKHZk = ~ + rrk |
(k = 0, ±1, ±2, ...), H TO'lKaZ = 00. |
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a) TaK KaK |
lim |
cos Z = 0, TO |
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z--+zk=~+11"k |
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lim |
CO~Z = 00, k = 0, ±1, ±2, .•• ; |
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Z--+Zk |
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3Ha'lHT,K~AM TO'lKaZk = ~ + rrk flBJIfleTCfl rrOJIIOCOM. |
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OrrpeAeJIHM rropflAOK K~AOro rrOJIIOca. HaiiAeM rrpeAeJI |
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lim |
(I + rrk) r- |
[t = |
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2 |
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= t+ |
2 + rrk,] |
= |
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[Z - |
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- |
Z - |
zr. - rrk ¢} Z |
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t -+ |
zr. |
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z--+2"+11"k |
COSZ |
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Z -+ zr.2 + rrk |
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° |
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11" |
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¢} |
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= lim |
t |
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= lim |
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t |
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1 |
lim _t_ = |
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t--+o cos |
(t + I + rrk) |
HO (_l)k+l sin t |
(_l)k+l HO sint |
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= |
1 |
#0 (k = 0, ±1, ±2, |
••. ). |
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(_l)k+l |
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CJIeAOBareJIhHO, K~AM H3 TO'leKZk :;= |
~ +rrk (k = 0, ±1, ±2, ...) flBJIfleTCfl |
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rrOJIIOCOM 1-ro rropflAKa.
6) TO'lKaZ = 00 flBJIfleTCfl rrpeAeJIhHOii AJIfl rrOCJIeAOBaTeJIhHOCTH rrOJIIOCOB - TO'leKZk = ~ +rrk, CJIeAOBaTeJIhHO, Z = 00 He flBJIfleTCfl H30JIHpOBaH-
Hoii oco6oii TO'lKOii. •
HafJ.mu Bce oco6'bte mo"t'ICu !PYH'IC't!UU J(z) U onpeae.aumb UX mun, a.!IJI. nO.lI,'IOCa HafJ.mu e20 nop.Rao'IC.
7.4.26. |
z2 - |
4 |
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7.4.27. |
J(z) = |
Z2 +4 |
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J(z) = -- 2' |
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-- 2" |
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z- |
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7.4.29. |
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z - |
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z |
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7.4.28. |
1 |
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J(z) = (z _ l)(Z + 2)2' |
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J(z) =~. |
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z |
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7.4.30. |
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J(z) = sh - 2 - ' |
7.4.31. |
J(z)=e z. |
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-1 |
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7.4.32. |
J(z) = si~z' |
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7.4.33. |
J(z) = |
1 - |
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. (Z5 + 3). |
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z5 |
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7.4.34. |
z-2 |
1 |
7.4.35. |
J(z) = |
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J(z) = -- 2 cos z' |
2 |
- |
4) |
2 sh -- 1 • |
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l+z |
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(z |
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z- |
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474
7.4.36. |
eZ -1 |
7.4.37. J(z) = z3 ctg z ! l' |
J(z) = - z - ' |
7.4.38.J(z) = eZ-~.
Hai1.mu pa3.!tcr.JfCeHUe !PYH'IC'qUU J(z) a p.Ra JIopaHa a mO"l.'lCe Zo no CmeneH.RM z - zoo Y'lCa3am'b 2.!taaHY'IO U npaau.!t'bHy'lO "I.acmu p.Raa U e20 o6.!tacm'b cxoau-
.Mocmu.
7.4.39. |
J(z) = |
\ eZ , |
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z |
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6) Zo = 00. |
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a) Zo = 0, |
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1 |
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7.4.40. |
J(z) = ze z - |
i , Zo = i. |
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7.4.41. |
J(z) = (z + 2)2 sin z2 + 4z ~ 5, Zo = -2. |
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z + 22i, |
(z + 2) |
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7.4.42. |
J(z) = |
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z- |
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6) Zo = 00. |
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a) Zo = 2, |
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7.4.43. |
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z - |
2i |
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J(z) = (z + |
2i)3' Zo = -2z. |
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7.4.44. |
( |
2 + 3i |
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Jz)= z+ 1 -z.,zo=z. |
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7.4.45. |
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1 |
+ 2)' Zo = 00. |
J(z) = (z _ l)(z |
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7.4.46. |
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z-2 |
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J(z) = (z _ l)(z |
+ 2) , Zo = z. |
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Hai1.mu ace oco6'bte mo"l.'lCu !PYH'IC'qUU J(z), onpeae.!tum'b ux mun, a.!t.R no.!t'lOca HafJ,mu e20 nop.Rao'IC.
7.4.47. |
z2 - Z - 6 |
7.4.48. |
2+i |
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J(z) = |
J(z) = (z _ i)2(Z + 3)5 |
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7.4.49. |
z2 + 1 |
7.4.50. |
J(z) = e- z2 • |
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J(z) = cos -- 2 . |
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7.4.51. |
J(z) = tgz. |
7.4.52. |
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J(z) = sinz - |
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7.4.53. MO:>KeT JIM pa3JIO:>KeHMe HeKOTopoii <PYHKIJ;MM B p.H,l1. JIopaHa CO,l1.ep-
:>KaTb:
a) KOHe'lHOe 'IMCJIO CJ1araeMbIX C OTpMIJ;aTeJIbHbIMM CTeneH.HMM
(z - zo);
6) KOHe'lHOe 'IMCJIO CJIaraeMbIX C nOJIO:>KMTeJIbHbIMM CTeneH.HMM
(z - zo);
475
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B) 6eCKOHeqHOe qHCJIO CJIaraeMbIX C OTpHIJ;aTeJIbHbIMH CTerreH5IMH |
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(Z - |
Zo); |
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r) 6eCKOHeqHOe qHCJIO CJIaraeMbIX C rrOJIO)KHTeJIbHbIMH CTerreH5IMH |
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zo)? |
=f. 00 - |
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7.4.54. |
IIycTb Zo |
H30JIHpOBaHHruJ oco6ruJ TOqKa cPYHKIJ;HH J(z). |
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Orrpe,l1.eJIHTb THrr 9TOft oco6oft TOqKH, eCJIH pa3JIO)KeHHe cPYHKIJ;HH |
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J(z) |
B p5l,l1. JIopaHa B OKpeCTHOCTH Zo CO,l1.ep)KHT: |
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a) KOHeqHOe qHCJIO CJIaraeMbIX C rrOJIO)KHTeJIbHbIMH CTerreH5IMH |
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(z - |
zo) H KOHeqHOe (=f. |
0) |
qHCJIO CJIaraeMbIX C OTpHIJ;aTeJIbHbIMH |
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CTerreH5IMH (z - zo); |
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6) 6eCKOHeqHOe qHCJIO CJIaraeMbIX C rrOJIO)KHTeJIbHbIMH CTerreH5I- |
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MH (z - |
zo) H 6eCKOHeqHoe qHCJIO CJIaraeMblX C OTpHIJ;aTeJIbHbIMH |
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CTerreH5IMH (z - zo); |
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B) TOJIbKO 6eCKOHeqHOe qHCJIO CJIaraeMbIX C rrOJIO)KHTeJIbHbIMH |
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CTerreH5IMH (z - zo). |
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7.4.55. |
IIycTb Cn |
(n = 0, ±l, ±2, ...) - |
K09cPcPHIJ;HeHTbI pa3JIO)KeHH5I B |
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p5l,l1. JIopaHa cPYHKIJ;HH |
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+00 |
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J(z) = L |
cn(z - |
zo)n. |
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n=-oo |
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HaftTH K09cPcPHIJ;HeHTbI c~ pa3JIO)KeHH5I B p5l,l1. JIopaHa cPYHKIJ;HH: |
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a) (z - |
zo)J(z); |
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6) (z - |
zo)3 J(z); |
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B) _l-J(z); |
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z - |
Zo |
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r) ( |
z - |
1 |
)m J(z) |
(m - |
HaTYPaJIbHOe qHCJIO). |
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7.4.56. |
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Zo |
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HaftTH MHO)KeCTBO TOqeK, B KOTOPbIX CXO,l1.HTC5I p5l,l1. JIopaHa: |
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+00 |
zn |
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+00 |
zn |
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a) n=~oo |
3n + 1; |
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6) n=~oo n 2 + 1 ; |
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B) |
+00 |
2n z n . |
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L |
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n=-oo |
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7.4.57. "YKa3aTb THrr oco6oft TOqKH Zo ,l1.JI5I cPYHKIJ;HH J(z) + g(z), eCJIH TOqKa Zo 51BJI5IeTC5I:
a) YCTpaHHMoft oco6oft TOqKOft ,l1.JI5I J(z) H YCTpaHHMofi oco6ofi TOqKOfi ,l1.JI5I g(z);
6) YCTpaHHMoft oco6ofi TOqKOfi ,l1.JI5I J(z) H rrOJIIOCOM ,lI..JI5I g(z);
B) YCTpaHHMoft oco6ofi TOqKOfi ,l1.JI5I J(z) H cymecTBeHHO oco6oft TOqKOfi ,l1.JI5I g(z);
r) rrOJIIOCOM ,l1.JI5I J(z) H cymecTBeHHO oco6ofi TOqKOfi ,lI..JI5I g(z);
)I.) rrOJIIOCOM n-ro rrOp5l,l1.Ka ,lI..JI5I J(z) H rrOJIIOCOM m-ro rrOp5l,l1.Ka ,lI..JI5I g(z).
7.4.58. MO)KeT JIH TOqKa Zo 6bITb oco6ofi TOqKOft YKa3aHHbIX THrrOB ,l1.JI5I
,l1.aHHbIX cPYHKIJ;Hfi:
a) rrOJIIOCOM ,l1.JI5I J(z) H rrOJIIOCOM ,lI..JI5I (z - zo)J(z);
476
6) nOJIIOCOM )l,JI5I J(z) H YCTpaHHMoit oc060it TOqKOit
)l,JI5I (z - zo)J(z)j
B) nOJIIOCOM )l,JI5I J(Z) H Cyrn;ecTBeHHO oc060it TOqKOit
)l,JI5I (Z - ZO)J(Z)j
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r) |
Cyrn;ecTBeHHO oc060it TOqKOit )l,JI5I J(Z) H Cyrn;ecTBeHHO oc060it |
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TOqKOit )l,JI5I |
(Z - |
ZO)J(Z)j |
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~) YCTpaHHMoit oc060it TOqKOit )l,JI5I J(Z) H YCTpaHHMoit oc060it |
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TOqKOit )l,JI5I |
_1_ J(z) j |
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Z - |
Zo |
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e) YCTpaHHMoit oc060it TOqKOit )l,JI5I J(z) H nOJIIOCOM |
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)l,JI5I _1_ J(z)j |
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Z - Zo |
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>K) YCTpaHHMoit oc060it TOqKOit )l,JI5I J(z) H cyrn;ecTBeHHo oc060it |
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TOqKOit )l,JI5I _1-J(z)? |
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Z - |
Zo |
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7.4.59. |
IIycTb TOqKa Zo |
51BJI5IeTC5I nOJIIOCOM k-ro nOp5l)l,Ka )l,JI5I <PyHKIJ;HH |
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J(z). YKa3aTb THn oc060it TOqKH Zo )l,JI5I <PYHKIJ;HH: |
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a) |
(z - zo)J(z)j |
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6) (z - zO)3 J(Z)j |
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B) |
Z! Zo J(Z)j |
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r) |
(z -\0)5 J(z). |
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7.4.60. |
Onpe)l,eJIHTb THn oc060it TOqKH Zo = 0 )l,JI5I <PyHKIJ;HH ~1-_._1_. |
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e - |
SlllZ |
7.4.61. |
Onpe)l,eJIHTb THn oc060it TOqKH Zo = ~ )l,JI5I <PyHKIJ;HH |
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1 |
( |
7r)-2 |
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COSZ - |
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Z - "2 |
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7.4.62. |
IIycTb Zo - |
H30JIHpOBaHHa51 oc06a51 TOqKa <PyHKIJ;HH J(z). ,Il;oKa- |
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3aTb, 'ITOeCJIH J(z) OrpaHHqeHa B OKpeCTHOCTH TOqKH Zo, TO Zo - |
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YCTpaHHMM oc06a51 TOqKa )l,JI5I J(z). |
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7.4.63. |
IIycTb Zo - |
H30JIHpOBaHHa51 OC06M TOqKa <PyHKIJ;HH J(z). ,Il;oKa- |
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3aTb, 'ITOeCJIH |
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IJ(z)1 < |
1 |
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(z _ zo)m |
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(m - HaTypaJIbHOe qHCJIO) B HeKoTopoit OKpeCTHOCTH TOqKH Zo,
TO Zo - JIH60 YCTpaHHMa51 oc06a51 TOqKa, JIH60 nOJIIOC )l,JI5I <PYHKIJ;HH
7.4.64. ,Il;oKa3aTb, 'ITO<PYHKIJ;H5I aHaJIHTHqeCKM BO Bceit KOHeqHoit KOMnJIeKcHoit nJIOCKOCTH H HMeIOrn;a51 B TOqKe Zo = 00 nOJIIOC nOp5l)l,Ka n, 51BJI5IeTC5I MHOrOqJIeHOM CTeneHH n.
§ 5. BblYETbl
=? IIycTb <PYHKIJ;HH J(z) aHaJIHTIPIHa B HeKoTopolt rrpOKOJIOTolt OKpeCTHOCTH U
KOHeqHolt TO'lKHzoo B'b/,"I,emOM (/jy'ltICv,uu J(z) |
6 mO"l,ICe Zo Ha3bIBaeTCH '1HCJIO |
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1 |
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1 |
j |
J(z) dz, |
res J(z) = - 2. |
jJ(z) dz = - 2. |
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zo |
7rt |
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7rt |
Iz-zol=p |
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'Y |
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477
I',D;e'Y - HeKoTopbIit 3aMKHYTbdl: KOHTyp, U:eJIHKOM JIe)l{am:Hit B U H CO,D;ep)l{am:Hit BHyTpH TO'IKYzo, a Iz - zol = p - OKPY)l{HOCTb C u:eHTPOM B TO'IKeZo ,D;OCTaTO'I-
HO MaJIOI'Opa,D;Hyca p, U:eJIHKOM JIe)l{am:aH B U. 06xo,D; KOHTypa 'Y H OKPY)l{HOCTH
npOH3BO,D;HTCH npomUB "acoBoit cmpe.ll7CU. ~
3Ha'IeHHH060HX npHBe,D;eHHbIX HHTeI'paJIOBnpH YKa3aHHbIX YCJIOBHHX COBna- ,D;aIOT.
ECJIH <PYHKU:HH J(z)
C-k |
k + ... + |
C-2 |
C-l |
() |
( |
Z-ZO |
)n |
... , |
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f ( z ) = ... + |
ZO) |
(Z - ZO) |
2 + --- +CO+Cl Z-ZO .. .+Cn |
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(Z - |
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Z - Zo |
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TO resJ(z) = C-l. |
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(5.1) |
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:0 |
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~ IIycTb <pyHKU:HH J(Z) aHaJIHTH'IHaB HeKoTopoit npOKOJIOTOit OKpeCTHOCTH U 6ecKOHe'IHOy,D;aJIeHHoit TO'IKH00. B'b/,,,emo.M ¢YH.7C'IJ,UU J(Z) B mO"7Ce 00 Ha3bIBaeTCH
'IHCJIO |
J(z) = |
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!J(z) dz = |
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! J(z) dz, |
00 |
1 |
1 |
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7rZ |
7rZ |
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res |
- 2. |
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- 2. |
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"I |
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1:I=p |
I',D;e'Y - HeKoTopbIit |
3aMKHYTbIit |
KOHTyp, a |
Izl = p - OKPY)l{HOCTb ,D;OCTaTO'IHO |
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60JIbllOI'Opa,D;Hyca, U:eJIHKOM JIe)l{am:aH BU. 06xo,D; KOHTypa H OKPY)l{HOCTH npo-
H3BO,D;HTCH no "acoBoit cmpe.ll7Ce. ~
3Ha'IeHHH060HX npHBe,D;eHHbIX HHTeI'paJIOBnpH YKa3aHHbIx YCJIOBHHX COBna- ,D;aIOT.
ECJIH pa3JIO)l{eHHe (5.1) CXO,D;HTCH B HeKoTopoit OKpeCTHOCTH TO'IKH00, TO
resJ(z) = -C-l.
00
EClllII <PYHK~lIIfl J(z) aHalllllTIII'lHaHa BCeiii KOMnlleKCHoiii nllOCKOCTIil
C. sa IIICl(JUO'leHllleMIIISOlllllpOBaHHblX OC06blX TO'leKZl, Z2, . .. Zn. TO
|
n |
resJ(z) = - L res J(z). |
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00 |
k=l :k |
ECJIH <PYHKU:HH J (Z) aHaJIHTH'IHaB TO'IKeZo HJIH eCJIH Zo - YCTpaHHMaH oco6ax
TO'IKa,D;JIHJ(Z), TO
resJ(z) =0.
:0
TeopeMa 7.5. EClllII |
TO'lKa Zo - |
nOlllOC |
k-ro nopflAKa (k |
> 1) Allfl <PYHK~IIIIII |
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J(z). TO |
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d'<-l [J(z)(z - Zo)k] |
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1 |
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res J(z) = ( |
)' hm |
dz |
k-l |
. |
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:0 |
k - |
1 . :-+:0 |
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478
ECJIH Zo - IIOJIIOC l-ro IIOpH)l;Ka)l;JIH <PYHKU:HH J(Z), TO
resJ(z) = lim [J(z)(z-zo)],
zo z---+zo
rp(z)
a eCJIH em;e H3BeCTHO, 'ITO<PYHKU:HH J(z) IIpe)l;CTaBHMa B BH)l;e J(z) = t/J(z)' r)l;e
<PYHKU:HH rp(z) H t/J(z) - aHaJIHTHqeCKHe B TOqKe zo, t/J(zo) = 0, t/J'(zo) =I 0, TO
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rp(zo) |
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res J(z) = ---;---(). |
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zo |
t/J |
Zo |
qacTO IIpH BblqHCJIeHHH HHTerpaJIOB OT <PYHKU:Hit KOMIIJIeKCHOro IIepeMeHHoro IIpHMeHHIOT CJIe)l;JIOIIJ;yIO TeopeMY.
TeopeMa 7.6 (OcHoBHaR TeopeMa 0 BbllieTax). nYCTb <PYHK~~"I J(z) - |
aHalllll- |
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TIII'leCKal'lB |
OAHOCBI'ISHOA 0611aCTIil D sa IIICKlllO'leHllleM HeKOTopblX IIISOlllllpOBaH- |
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HblX OC06blX |
TO'leK; l - npOCTal'l saMKHYTal'l KpIIIBal'l, ~ellIllKOM lle>Ka~al'l |
B D III |
He npoxOAI'I~al'l 'lepesoco6ble TO'lKIil <PYHK~IIIIII J(z). TorAa
f |
J(Z)dz = 27ri· tresJ(z), |
Zk |
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I |
k=l |
7.5.1.HaiiTIi Bhl'leThI <PYHKIJ;IIII
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( |
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z + 1 |
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f z) = |
(z + 2i)2(Z _ 1) |
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BO Bcex OC06hIX TO'iKax II onpe,n:e.ITIiTh IIX Tlln, HaiiTIi BhlqeT B 6ec- |
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KOHe'iHO y,n:a.neHHoii TO'iKe. |
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Q OC06hIMH |
TO'iKaMIi |
<PYHKIJ;IIII f (z), |
O'ieBII,n:HO, |
.HB.IT.HIOTC.H C.ITe.n:yIOID;lIe |
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TO'iKII: |
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-2i - |
nO.ITIOC 2-ro nOp.H,n:Ka, |
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1 - |
nO.ITIOC 1-ro nopH,n:Ka. |
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Haii,n:eM BhI'ieT B TO'iKe -2i: |
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res.f(z) = lim. [f(z)(z - (-2i))2] |
, |
= |
[(Z+1)(Z+2i)2]' |
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lim. |
( |
.)2( |
z - |
) |
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-2t |
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z-+-2t |
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z-+-2t |
Z + 2z |
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1 |
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= |
. |
(z+l)' |
. l·(z-l)-l·(z+l) |
= |
. |
-2 |
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hm |
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-- |
= |
hm |
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(z - |
1)2 |
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hm |
---=~ = |
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z-+-2i |
Z - 1 |
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z-+-2i |
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z-+-2i |
(z - 1)2 |
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-2 |
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-2 |
= |
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2 |
2 |
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(-2i - |
1)2 |
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(1 + 2i)2 |
1 + 4i - |
4 = 3 - 4i; |
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479
