Сборник задач по высшей математике 2 том
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no 3aMKHYToil: KPRBOil: I, RCnOJIb3YH cP0PMYJIbI (3.4)-(3.6) (06xo,a; |
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KPRBOil: ocyru;eCTBJIHeTCH npOTRB qacOBOil: CTpeJIKR). |
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a) I: |
Iz - 21 |
= 1; |
6) I: Izl = 1; |
B) I: |
Iz + 21 |
= l. |
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a a) TaK KaK no,a;bIHTerpaJIbHaH cPYHKD:RH |
1 |
3 |
z |
aHaJIRTRqHa Ha Bceil: |
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(z |
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KOMnJIeKcHoil: nJIOCKOCTR C, 3a RCKJIlOqeHReM TOqeK (-2) R 0, KOTopble He |
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JIe)l{aT BHyTpH OKPY)l{HOCTH Iz - 21 |
= 1 R Ha 9TOil: OKPJ)KHOCTR, TO no TeopeMe |
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KOllm nOJIyqRM: |
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dz |
-0 |
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(z + |
2)3 Z |
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Iz-21=1 |
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6) TaK KaK cPYHKD:HH j (z) |
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3 aHaJIRTHqeCKaH Ha Bceil: KOMnJIeKC- |
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(z + 2) |
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HOil: nJIOCKOCTH C, 3a RCKJIlOqeHReM TOqKR (-2), KOTOPaH He JIe)l{RT BHYTPR |
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OKPJ)KHOCTH Izl = 1 R Ha 9TOil: OKPJ)KHOCTR, a TOqKa Zo = 0 JIe)l{HT BHYTPH |
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9TOil: OKPY)I{HOCTR, TO no RHTerpaJIbHoil: cPopMYJIe KOllm nOJIyqRM: |
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J |
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1 |
(z + 2)3 |
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j(zo = 0) = -2. |
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z- |
0 |
dz, |
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7rZ |
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Izl=l |
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oTKy,a;a |
J (z :~)3Z = 27ri· j(zo = 0) = 27ri· (0: 2)3 |
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= 27ri· ~ = ~. |
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Izl=l |
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= i |
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B) TaK KaK cPYHKD:HH j(z) |
aHaJIRTRqHa |
Ha Bceil: KOMnJIeKcHoil: |
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nJIOCKOCTH C, |
3a RCKJIlOqeHReM HYJIeBoil: TOqKR, KOTOPaH He JIe)l{RT BHYTPH |
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OKPY)I{HOCTR |
Iz + 21 |
= 1 R Ha 9TOil: OKPY)I{HOCTH, a |
TOqKa Zo = -2 JIe)l{RT |
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BHYTPH 9TOil: OKPJ)KHOCTR, TO no cPopMYJIe (3.6) nOJIyqRM: |
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f |
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j |
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Zo |
= - |
2) |
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2! |
(z |
Z |
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d |
z, |
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= 27ri |
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2)3 |
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1Z+21=1 |
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f |
dz |
= 27ri /"(zo = -2) = 7ri· (1)" 1 |
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(z + 2)3 z |
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2! |
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Z |
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zo=-2 |
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Iz+21=1 |
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= 7ri· (-1..)' 1 |
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= 7ri· .1.1 |
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= 7ri. _2_ = _7ri.. |
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Z2 |
zo=-2 |
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z3 |
zo=-2 |
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(_2)3 |
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B'bt"tuC.ltUmb u1tmezpa.lt'bt: |
I - |
OTpe30K |
npHMoil: OT TOqKH Zl |
o ,a;o TOqKH |
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7.3.8. |
Re z dz, |
r,a;e |
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I
Z2 = i.
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7.3.9.jIrnzdz, r)1.e:
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a) l |
- |
OTpe30K np.aMoti OT TO'IKHZl = |
2 |
)1.0 TO'IKHZ2 |
= |
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6) l |
- |
OTpe30K np.aMoti OT TO'IKHZl = |
0 |
)1.0 TO'IKHZ2 |
= |
1 + |
i; |
B) l - .rryra napa60JIbI y = x 2 OT TO'IKHZl |
= 0)1.0 TO'IKHZ2 = |
1 +i. |
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7.3.10. jcz + |
z) dz, r)1.e: |
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a) l |
- |
OTpe30K np.aMoti OT TO'IKHZl = |
0 |
)1.0 TO'IKHZ2 |
= |
-1 + i; |
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6)l - .rryra napa60JIbI y=x2 OT TO'IKHZl =0)1.0 TO'IKHZ2 = -1 +i.
7.3.11.jlzl dz, r)1.e:
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a) |
l |
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.rryra OKPY:>KHOCTH Izl = 1 OT |
TO'IKH Zl = |
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1 )1.0 TO'IKH |
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Z2 |
= -1; |
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6) |
l |
- |
OTpe30K np.aMoti OT TO'IKHZl |
= |
1 )1.0 TO'IKHZ2 |
= |
-1; |
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B) l |
- |
OTpe30K np.aMoti OT TO'IKHZl |
= |
0 )1.0 TO'IKHZ2 |
= |
2 - 2i. |
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7.3.12. |
j~Z, r)1.e l - .rryra OKpY:>KHOCTH Izi = |
2 OT TO'IKHZl |
= |
2)1.0 TO'IKH |
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= 2e27ri • |
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Z2 |
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7.3.13. |
jlzI 2dz, |
r)1.e l - |
OTpe30K np.aMoti |
OT TO'IKH Zl = |
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0 |
)1.0 TO'IKH |
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Z2 = V2ei i. |
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7.3.14. |
jCz2 - |
z) dz, r)1.e l |
- |
OTpe30K np.aMoti OT TO'IKHZl |
= |
0 )1.0 TO'IKH |
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Z2 |
= i. |
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7.3.15. |
jC2i - |
z) dz, r)1.e l |
- |
OTpe30K np.aMoti OT TO'IKHZl |
= |
0 |
)1.0 TO'IKH |
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+ i. |
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Z2 = 1 |
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7.3.16. |
j ReCz 2 - |
z) dz, r)1.e l |
- )1.yra napa60JIbI y = 2X2 OT TO'IKHZl = 0 |
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)1.0 TO'IKHZ2 = 1 + |
2i. |
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7.3.17. |
Jciz 2 + |
2z) dz, r)1.e l - |
OTpe30K np.aMoti OT TO'IKHZl = |
0 )1.0 TO'IKH |
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+ i. |
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Z2 |
= 1 |
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7.3.18. |
jCz2 - |
3iz) dz, r)1.e l - |
OTpe30K np.aMoti OT TO'IKHZl |
= |
1 )1.0 TO'IKH |
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Z2 |
= i. |
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7.3.19. |
jCz3 - |
1) dz, r)1.e l - |
OTpe30K np.aMoti OT TO'IKHZl |
= |
0 )1.0 TO'IKH |
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+i. |
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Z2 |
= 1 |
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7.3.20. |
jCiz3 + 3) dz, r)1.e l - |
OTpe30K np.aMoti OT TO'IKHZl |
= |
1 )1.0 TO'IKH |
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I |
= i. |
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Z2 |
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7.3.21. |
I |
e Z dz, |
r)1.e l |
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OTpe30K rrpHMoit OT TOqKH Zl = i |
)1.0 TOqKH Z2 = |
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= 1 +i. |
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7.3.22. |
IZ eZ dz, |
r)1.e l |
- |
OTpe30K rrpHMoit OT TOqKH |
Zl |
o )1.0 |
TOqKH |
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7r. |
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Z'J |
= 2"z. |
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7.3.23. |
ISinzdz, r)1.e l |
- |
OTpe30K rrpHMoit |
OT TOqKH |
Zl |
0)1.0 |
TOqKH |
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= i. |
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Z2 |
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o )1.0 |
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7.3.24. |
Ichzdz, |
r)1.e |
l |
- |
OTpe30K rrpHMoit |
OT |
TOqKH |
Zl |
TOqKH |
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I |
= 7r - |
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Z2 |
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7ri. |
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HCnOJI,'b3YJI |
aHaJl.Umu"tHOCm'b |
nOa'btHmeZpM'bHoiJ. tjiYH'X:V,UU, |
6'bt"tUCJl.Um'b UH- |
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mezpaJl.'bt: |
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7.3.25. |
l(iz3 + 3) dz, r)1.e l - OTpe30K rrpHMoit OT TOqKH Zl = 1 )1.0 TOqKH |
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Z2 = i (CM. TaIOKe 3a)1.aqy 7.3.20). |
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7.3.26. |
IChzdz, |
r)1.e |
l |
- |
OTpe30K rrpHMoit |
OT |
TOqKH |
Zl |
0 )1.0 |
TOqKH |
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Z2 = 7r - |
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7ri (CM. TaK:>Ke 3a)1.aqy 7.3.24). |
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7.3.27. |
IZ3 dz, r)1.e l |
- |
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~ |
= 1 OT TOqKH Zl = 2i )1.0 |
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qacTb 9JIJIHrrCa ~ + '4 |
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= -3 (06xo)1. ocyrn;eCTBJIHeTCH rrpOTHB qaCoBoit CTpeJIKH). |
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TOqKH Z2 |
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B'bt"tucJl.um'b UHmeZpaJl.'bt: |
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- OTpe30K rrpHMoit OT TOqKH Zl = I )1.0 TOqKH |
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7.3.28. |
I(z - z) dz, r)1.e l |
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Z2 = 27r. |
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OTpe30K rrpHMoit OT TOqKH Zl = 0 )1.0 TOqKH Z2 = |
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7.3.29. |
Ilzl dz, r)1.e l - |
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= 3 + 2i. |
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)l.yra OKPY:>KHOCTH Izl |
= 1 OT TOqKH |
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= 1 )1.0 |
7.3.30. |
I zlzl dz, |
r)1.e l |
- |
Zl |
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TOqKH Z2 = e21ri |
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TOqKH Zl = 0 |
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7.3.31. |
IIzl2 dz, |
r)1.e l |
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OTpe30K rrpHMoit OT |
)1.0 |
TOqKH |
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Z2 = J3 + i.
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7.3.32. |
!(iz2 + z) dz, r)1.e l - |
OTpe30K rrpjlMoit OT TO'lKH Zl |
= i )1.0 TO'lKH |
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= 1. |
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Z2 |
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7.3.33. |
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Re z· Irn(z2) dz, r)1.e l - .rr.yra rrapa60JIbI Y = 2x3 OT TO'lKH Zl = 0 |
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)1.0 TO'lKH Z2 = 1 + 2i. |
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7.3.34. |
!Irnzdz, r)1.e l - |
.rr.yra OKPY:>KHOCTH Izl = 3 OT TO'lKH |
Zl |
= 3)1.0 |
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TO'lKH Z2 = 3e27ri . |
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7.3.35. |
! |
eZ dz, r)1.e l - |
OTpe30K rrpjlMoit OT TO'lKH Zl |
0 |
)1.0 |
TO'lKH |
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= 7r + 7ri. |
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Z2 |
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7.3.36. |
!Re(sinz) coszdz, r)1.e l - OTpe30K rrpjlMoit OTTO'lKH Zl |
= ~(7r-i) |
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)1.0 TO'lKH Z2 = ~(7r + i). |
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7.3.37. |
! |
z sin 2z dz, r)1.e l |
- |
oTpe30K rrpjlMoit OT TO'lKH Zl |
= 3 )1.0 TO'lKH |
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Z2 = 1 + i (<pYHKIJ;HjI z sin 2z aHaJIHTH'IHa B q. |
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B'bt"tuc.IIum'b u'ttmezpa.ll'bt no 3a.M'IC'ttymoti 'lCPU60ti, UCnO.ll'b3YSl rjjoPMY.ll'bt (3.4), (3.5) U.!IU (3.6) (o6xoiJ 'lCpU60ti oCY'lll,ecm6.!tS1emCSl npomU6 "taco6oti cmpe.!l'ICu).
7.3.38. |
f |
sin z . sin(z - |
1) dz. |
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Izl=2 |
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z(z - 1) |
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7.3.39. |
f |
sinz2 |
dz |
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(Z2 |
+ 7r )2 . |
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Iz - 7ril |
= 1; |
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a) l: |
Izl |
= 1; |
= 1. |
6) l: |
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0) l: |
Iz + 7ril |
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7.3.40. |
f Z5 dz- Z3' |
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I |
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a) l: |
Izl |
= ~; |
6) l: |
Iz |
- 11 |
= 1; |
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Iz |
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0) l: |
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+ 11 = 2' |
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7.3.41. |
f z ~1 dz. |
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a) l: |
Izl |
= ~; |
6) l: |
Izl |
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7.3.42. |
f cos z |
dz. |
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Z-7r |
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Iz - 7r1 |
= 1; |
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= 1. |
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a) l: |
6) l: |
Izl |
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7.3.43. |
f |
zdz |
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(z - 1)2· |
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I |
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= ~; |
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Izl |
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a) 1: |
Izl |
6) 1: |
= 2. |
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7.3.44. |
f |
Sinz dz |
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z |
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I |
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Izl = |
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Iz |
- |
11 |
= ~. |
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a) 1: |
1; |
6) 1: |
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7.3.45. |
f |
Sinz dz |
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z3 . |
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I |
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Izl = 1; |
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Iz |
- |
11 |
1 |
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a) 1: |
6) 1: |
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= '2. |
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7.3.46. |
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dz |
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= 1; |
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7.3.47. |
f |
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= 1; |
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7.3.48. |
f (z |
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+ 1)3(z - 1)2· |
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= 1; |
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= ~. |
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KOHTponbHble BonpOCbl M 60nee CnO)l(Hbie 3aAaHMH
7.3.49. IIycTb h - .rryra HeKoTopoit KPHBOit 1 C HaqanbHoit TOqKOit ZI H KOHeqHoit TOqKOit Z2, a 12 - .rryra TOit JKe KPHBOit C HaqanbHoit TOqKOit Z2 H KOHeqHoit TOqKOit ZI (MHOJKeCTBa TOqeK Ha 11 H 12
COBna,n,aIOT). qTO MOJKHO CKa3aTb 06 HHTerpanax
!J(z) dz H |
!J(z) dz? |
h |
12 |
7.3.50. qTO MOJKHO CKa3aTb 06 HHTerpane
!ReJ(z) dz,
I
r)1;e 1- OTpe30K Ha MHHMOit OCH, a ¢YHKII;HjI J(z) HenpepbIBHa Ha
9TOM OTpe3Ke?
7.3.51. ECJIH
fJ(z)dz = 0,
I
464
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CJIe.rr.yeT JHI M3 9TOrO, 'ITOf Cz) - aHaJUITM'IeCKruI<PYHKUM.a BHYTPM |
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3aMKHYToit KPMBOit l? |
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7.3.52. |
,ILoKa3aTb paBeHcTBo: |
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f afCz) dz = a f |
fCz) dz. |
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I |
I |
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7.3.53. |
Bbl'lMCJIMTb f |
ctg z dz. |
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Izl=l |
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7.3.54. |
BepHO JIM, 'ITO)1;JI.a JIlo6oit <PYHKUMM fCz) M JIlo6oit KPMBOit l Bbl- |
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IIOJIH.aeTC.a HepaBeHCTBO: |
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a) flfCz)ldz ~ 0; |
6) f j2Cz)dz ~ O? |
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7.3.55. |
I |
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I |
BepHO JIM paBeHCTBO |
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j(hCz) + hCZ))2 dz = f /fCz) dz + 2 f hCz)hCz) dz + f /iCz) dz?
I I I I
§4. P~AbI1l0PAHA. Lil301lLilPOBAHHbiE OC06blE
TOYKLiI
~PSIiJOM JIopa'H,a Ha3blBaeTCH pH,lJ; BH,lJ;a
+00 |
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L cn(z-zot = ...+ |
C-k |
k +.. .+~+CO+C1(Z-ZO)+...+Cn(Z-zot+·.·, |
n=-oo |
(z - zo) |
z - Zo |
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(4.1) |
r,lJ;e Zo - <pHKcHpoBaHHaH TO'lKaKOMllJIeKcHoit llJIOCKOCTH C, a Cn ('1w3g}(jjuu,ue'H,m'bl.
pH,lJ;a JIopaHa) - |
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3a,lJ;aHHble KOMllJIeKCHble '1HCJIa. |
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PH,lJ; JIopaHa IIpe,lJ;CTaBJlHeT c060it CyMMy ,lJ;ByX PH,lJ;OB: pH,lJ;a |
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-1 |
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)n |
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C 1 |
C-2 |
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C- n |
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'" |
Cn |
Z - Zo |
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2 + ... + ( |
)n + ... |
(4.2) |
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L..J |
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= -- + |
(Z - |
ZO) |
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n=-oo |
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Z - Zo |
Z - Zo |
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H pH,lJ;a |
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+00 |
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ZO) + C2(Z - |
ZO)2 + ... + Cn(Z - |
zot +.... |
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L Cn(Z - zot = Co + C1(Z - |
(4.3) |
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n=O
PH,lJ; JIopaHa Ha3blBaeTCH CXOORU!UMCR B HeKoTopoit TO'lKeZ E C, eCJlH B 9TOit TO'lKeCXO,lJ;HTCH o6a 9THX pH,lJ;a (T. e. pH,lJ;bl (4.2) H (4.3)), IIpH 9TOM cyMMa pH,lJ;a (4.1) no ollpe)1;eJIeHHIO paBHa cyMMe ,lJ;ByX CJlaraeMblX - CYMMbl pH,lJ;a (4.2) H CYMMbl PH,lJ;a
465
TeopeMa 7.3 (.nopaH). ECIlIil cl>YHK~lIIfI |
J(z) aHallIllTIII'fHa B KOllb~e 0 ~ r < |
< Iz - zol < R, TO B 3TOM KOllb~e OHa npeACTaBIilMa CXOAfI~IIIMCfI PflAOM nOpaHa |
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+00 |
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J(z) = L |
Cn(Z - zot, |
n=-(X) |
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nplII'feM3TO npeACTaBlleHllle eAIIIHCTBeHHO; K03c1>cI>lII~lIIeHTbl Cn OAH03Ha'fHbIMo6pa30M OnpeAellfilOTCfI paBeHCTBaMIil
1 |
f |
J(z)dz |
Cn = 27ri |
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(z _ zo)n+1 ' r < p < R, n = 0, ±1, ±2, ... |
Iz-zol=p
liHOr,ll;a pH,lI; JIopaHa, CXO,ll;Hm;~dI:cH K q,YHKIJ;HH J(z)
~ r < Iz - zol < R, Ha3blBaeTCH PH,lI;OM JIopaHa ,lI;JlH J(z)
ECJIH q,YHKIJ;HH J(z) aHaJIHTH'lHaB Kpyre Iz - zol < R, TO pa3JIOJKeHHe J(Z) B
pH,lI; JIopaHa B ::ITOM Kpyre rrpe,ll;CTaBJIHeT co6oit pa3JlOJKeHHe J(Z) B pH,lI;, Ha3blBaeMblit PH,lI;OM TeitJIopa - B ::ITOM pa3JIOJKeHHH OTCYTCTBYIOT CJIaraeMble, CO,ll;epJKam;He OTpHIJ;aTeJIbHble CTerreHH (Z - ZO):
+00
J(Z) = L Cn(Z - zot = Co + C1(Z - ZO) + C2(Z - ZO)2 + ... + Cn(Z - zot + ...
n=O
~IIycTb O,ll;H03Ha'lHaH q,YHKIJ;HH J(Z) aHaJIHTH'lHa B HeKoTopoit rrpOKOJIOTOit
OKpeCTHOCTH TO'lKH Zo i= 00 (T. e. B HeKOTOpOM KOJIbIJ;e 0 < Iz - |
zol < R), HO |
He aHaJIHTH'lHaB TO'lKeZOo B 9TOM CJIY'laeTO'lKaZo Ha3bIBaeTCH U30JlUpOaa'H'Hoit |
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oco6oit mO"l,1Coit (O,ll;H03Ha'lHOrOXapaKTepa) ,lI;JIH q,YHKIJ;HH J(z). |
~ |
AHaJIOrH'lHO, 6eCKOHe'lHO Y,lI;aJIeHHaH TO'lKa(o603Ha'laeTCH3Ha'lKOM(0) Ha-
3blBaeTCH U30J1UpOaa'H'Hoit oco6oit mO"l,1Coit ,lI;JIH q,YHKIJ;HH J(z), eCJIH J(z) - O,ll;Ho-
3Ha'lHaHaHaJIHTH'leCKaHq,YHKIJ;HH B HeKOTopOM KOJIbIJ;e r < Iz - zol < +00 (zo -
HeKOTopaH TO'lKarrJIOCKOCTH C).
,n:aJIee B ::ITOM rraparpaq,e 6Y,lI;eM paCCMaTpHBaTb TOJIbKO O,ll;H03Ha'lHbleq,YHKIJ;HH.
~ rJlaa'Hoit "I,aCmb1O pH,lI;a JIopaHa B OKpeCTHOCTH H30JIHpOBaHHoit oco6oit TO'lKH (KOHe'lHoitHJIH 6eCKOHe'lHoit)Ha3blBaeTCH CYMMa Bcex Tex H TOJIbKO Tex 'lJIeHOB pH,lI;a JIopaHa, KOTopble CTpeMHTCH K 6eCKOHe'lHOCTHrrpH CTpeMJIeHHH z K oco6oit TO'lKe(T.e. pH,lI; (4.2) B CJIY'laeZo i= (0). IIpaauJlb'Hoit "I,aCmb1O pH,lI;a JIopaHa Ha3blBaeTCH cYMMa Bcex OCTaJIbHblX 'lJIeHOBpH,lI;a (T. e. pH,lI; (4.3) B CJIY'laeZo i=
TaKHM o6pa30M:
1) B oKpecTHocTH oco6oit TO'lKHZo i= 00:
-1 |
+00 |
J(z)= L Cn(Z-zot+Co+LCn(Z-Zoti |
|
n=-(X) |
n=l .. |
rJIaBHaH ~aCTb |
npaBHnbH&H ~acTb |
466
2) B oKpecTHocTH 6eCKOHe'lHOY)J;aJIeHHoi!: oco6oi!: TO'lKH00:
-1 |
+00 |
||
J(z) = L cn(z - |
zot + Co + L cn(z - zot; |
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n=-(X) |
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n=1 |
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----------- |
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rJl8BHaB ~aCTb |
(zo - HeKOTOpaH TO'lKanJIOCKOCTH C).
~IhoJIHpoBaHHaH oco6aH TO'lKaZo (KoHe'lHaHHJIH 6eCKOHe'lHaH)<PYHKIJ;HH J(z)
Ha3bIBaeTCH |
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1) |
ycmpaH,UMoi1. oco6oi1. mo'l,'lCoi1., eCJIH cYIIJ;eCTByeT KOHe'lHbli!:npe)J;eJI lim |
J(z); |
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Z~Zo |
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2) |
nO.ll70COM, eCJIH lim J(z) = 00; |
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z-+zo |
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3) |
cYUjecmt;leH,H,o oco6oi1. mo'l,'lCoi1., eCJIH npe)J;eJI lim J(z) He CYIIJ;eCTBYeT. |
~ |
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z--+zO |
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IhoJIHpoBaHHaH oco6aH TO'lKa(KOHe'lHaHHJIH 6eCKOHe'lHaH)HBJIHeTCH YCTpaHHMOi!: oco6oi!: TO'lKOi!:)J;JIH <PYHKIJ;HH J(z) Tor)J;a H TOJIbKO Tor)J;a, Kor)J;a rJIaBHaH '1acTbpH)J;a JIopaHa <PYHKIJ;HH J(z) B OKpeCTHOCTH oco6oi!: TO'lKHpaBHa HYJIIO (T.e. paBHbI HYJIIO Bce K09<P<PHIJ;HeHTbI Cn rJIaBHoi!: '1aCTH),T. e.:
1) )J;JIH oco6oi!: TO'lKHZo i= 00:
+00
J(z) = L cn(z - zot = Co + C1(Z - zo) + C2(Z - ZO)2 + ... ; n=O
2) )J;JIH 6eCKOHe'lHOY)J;aJIeHHoi!: oco6oi!: TO'lKH00:
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o |
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J() |
= |
,,()n |
C-1 |
C-2 |
2 + ... |
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Z |
L...J |
Cn Z-Zo |
=Co+---+ |
(z - zo) |
||
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n=-oo |
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Z - Zo |
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HeKOTopaH TO'lKanJIOCKOCTH C).
M30JIHpOBaHHaH Oco6aH TO'lKaZo HBJIHeTCH YCTpaHHMoi!: oco6oi!: TO'lKOi!:)J;JIH <PYHKIJ;HH J(z) B TOM H TOJIbKO B TOM CJIY'Iae,Kor)J;a 9Ta <PYHKIJ;HH aHaJIHTH'IeCKaHH
OrpaHH'IeHHaHB HeKoTopoi!: npOKOJIOToi!: OKpeCTHOCTH TO'lKHZo (T. e. B HeKOTopOM KOJIbIJ;e 0 < Iz - zol < R).
M30JIHpOBaHHaH oco6aH TO'lKaHBJIHeTCH nOJIIOCOM <PYHKIJ;HH J(z) Tor)J;a H TOJIb-
KO Tor)J;a, Kor)J;a rJIaBHaH '1aCTbpH)J;a JIopaHa <PYHKIJ;HH J(z) B OKpeCTHOCTH 9TOi!: TO'lKHCO)J;ep)KHT KOHe'lHOe(OTJIH'IHOeOT HYJIH) '1HCJIOHeHYJIeBbIX 'lJIeHOB,T. e.:
1) )J;JIH oco6oi!: TO'lKHZo i= 00:
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+00 |
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)n |
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J ( Z) |
= ( |
C-m |
)m + ( |
C- m +1 |
C - 1" ( |
Z - |
Zo |
; |
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Zo |
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) -1 + ... + - _ - + L...J Cn |
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z - |
z - |
Zo m |
Z Zo |
n=O |
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2) )J;JIH 6eCKOHe'lHOY)J;aJIeHHoi!: oco6oi!: TO'lKH00: |
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-1 |
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m |
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J(z) = L cn(z - |
zot + Co + C1 (z - |
zo)m-1 + cm(z - zo)m |
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zo) + ... C -1 (z - |
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n=-(X)
(Zo - HeKOTOpaH TO'lKanJIOCKOCTH C).
467
~qHCJIO m (HaH6oJIbllI3J'IH3 CTerreHeit CJlaraeMblX B rJIaBHoit '1aCTHpH.n;a JIopa-
Ha) Ha3blBaeTCH nopRf}7(;OM nO.II1Qca. ~
TO'lKaZo i= 00 HBJIHeTCH rrOJIIOCOM m-ro rropH.n;Ka (HJIH rropH.n;Ka m) q,YHKIJ;HH fez) Tor.n;a H TOJIbKO Tor.n;a, Kor.n;a <PYHKIJ;HH fez) rrpe.n;CTaBHMa B BH.n;e '1aCTHOro
<p(z) fez) = (Z - Zo )m'
r.n;e <PYHKIJ;HH <p(z) aHaJIHTH'IHaB TO'lKeZo, <p(zo) i= O.
ECJlH TO'lKaZo - rrOJIIOC rropH.n;Ka m <PYHKIJ;HH fez), TO zo- HYJIb KpaTHOCTH m <PYHKIJ;HH ftz). KpOMe Toro, TO'lKaZo- rrOJIIOC rropH.n;Ka m q,YHKIJ;HH fez), eCJIH
lim (z - zo)m fez) = C i= o.
z-+zo
BeCKOHe'lHOy.n;aJIeHH3J'ITO'lKa00 HBJIHeTCH rrOJIIOCOM m-ro rropH.n;Ka <PYHKIJ;HH fez) Tor.n;a H TOJIbKO Tor.n;a, Kor.n;a <PYHKIJ;HH fez) rrpe.n;CTaBHMa B BH.n;e rrpOH3Be.n;e- HHH
fez) = <p(z)(z - zo)m,
r.n;e <PYHKIJ;HH <p(z) aHaJIHTH'IHaB 6eCKOHe'lHOy.n;aJIeHHoit TO'lKe00, <pc00) i= O.
H30JIHpOBaHHaH oco6aH TO'lKaZo HBJlHeTCH cyw:eCTBeHHO oco6oit TO'lKOit<PYHKIJ;HH fez) TOr.n;a H TOJIbKO Tor.n;a, Kor.n;a maBHaH '1aCTbpH.n;a JIopaHa q,YHKIJ;HH fez) B OKpeCTHOCTH TO'lKHZo co.n;ep)l{HT 6eCKOHe'lHOe'1HCJIOHeHYJIeBbIX '1JIeHOBC OTpHIJ;a- TeJIbHblMH CTerreHHMH (z - zo) (.n;JIH oco6oit TO'lKHZo i= 00) HJIH C rrOJIO)l{HTeJIbHblMH CTerreHHMH (z - zo) ():\JlH 6eCKOHe'lHOy.n;aJIeHHoit TO'lKH00).
7.4.1. |
RaitTH pa3JIO:>KeHHe <PYHKI.J;HH \ sin Z B P.HJ.I: JIopaHa |
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Z |
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a) B oco6oit TOqKe Zo = 0; |
6) B oco6oit TOqKe 00. |
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YKa3aTb rJIaBHYIO H IIpaBHJIbHYIO qaCTH pH,ll;a Hero 06JIaCTb CXO- |
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,ll;HMOCTH. |
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a a) BOCIIOJIb3yeMcH H3BeCTHbiM pa3JIO:>KeHHeM <PYHKI.J;HH |
||
|
00 |
(-l)n |
|
sin Z = L |
z2n+1 |
n=O (2n + I)!
B pH,ll; (TeitJIopa) B 06JIaCTH 0 ~ Izl < +00, T. e. BO Bceit KOMIIJIeKcHoit IIJIOCKOCTH C:
rJlaSHaB qaCTb
npaBHJlbHaH ..aCTb
06JIaCTb CXO,ll;HMOCTH pH,ll;a - BCH KOMIIJIeKCHaH IIJIOCKOCTb C 3a HCKJIIO'ieHHeM TOqKH z = 0, T. e. KOJIbI.J;O 0 < Izl < +00.
468
6) ,I1;ml pa3JIOlKeHHH B pH,ll. JIopaHa B 6eCKOHeqHO Y,ll.aJIeHHoit TOqKH C,ll.e- |
||||||||||||
JIaeM 3aMeHY t = |
! |
H 6Y,ll.eM HCKaTb pa3JIO)KeHHe B TOqKe to |
= 0: |
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2 |
. 1 |
2 (1 |
- |
1 |
1 |
1 1 |
- |
... + |
(_I)n |
1 |
+ ... |
) |
t |
sm t = t |
t |
3! |
. t3 |
+ 51 . t5 |
(2n + I)! |
. t2nH |
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=t_.!..l+l.l_ ... + (_1)n |
._1_ |
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3! |
t |
5! |
t3 |
(2n + I)! |
t2n- 1' |
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OTKY,ll.a |
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\ |
sinz = |
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1 |
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z |
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z |
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......,.." |
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npaBH.nbHa:H qacTb
06JIaCTb CXO,ll.HMOCTH pH,ll.a- KOJIblJ;O 0 < Izl < +00.
KaK BH,ll.HM, B cJIyqae, KOr,ll.a pa3JIO)KeHHe B pH,ll. JIopaHa no CTeneHHM z
CXO,ll.HTCH B KOJIbue 0 < Izl < +00, OHO HBJIHeTCH O,ll.HOBpeMeHHo pa3JIO)KeHH-
eM H B TOqKe Zo = 0, H B TOqKe 00. |
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• |
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7.4.2. |
HaitTH pa3JIO)KeHHe <PYHKUHH -13 B PH)]. JIopaHa no CTeneHHM |
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-z |
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(z-l) B OKpeCTHOCTH TOqKH Zo = 1. YKa3aTb rJIaBHYIO H npaBHJIb- |
|||
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HYIO qaCTH pH,ll.a H era 06JIaCTb CXO,ll.HMOCTH. |
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Q CHaqaJIa BbI,ll.eJIHM Bblpa)KeHHe (z - |
1) B 3HaMeHaTeJIe ,ll.p06H -13 : |
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-z |
|
1 . 1 |
1 |
1 |
1 |
|
3 - z = 2 - (z - 1) = 2 (1 _ z; 1) = |
2· 1 _ z; 1 . |
||
Tenepb BOCnOJIb3yeMcH pa3JIO)KeHHeM ,ll.p06H |
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||
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00 |
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_1_ = "zn |
|
(4.4) |
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l - z |
~ |
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n=O
B 6eCKOHeqHO y6bIBalOI.II.Y1O reOMeTpHqecKYIO nporpeccHIO co 3HaMeHaTeJIeM q = z B TOit 06JIaCTH, r,ll.e z - «MaJIO» (T. e. B OTKPbITOM Kpyre q = Izl < 1).
B CHJIY BbIlIIeCKa3aHHora, ,ll.P06b
1
1- z -1
2
rrpe,ll.CTaBHMa B BH,ll.e pH,ll.a JIopaHa, CXOMrn;erOCH B 06JIacTH, r,ll.e Iql = Iz ; 11
«MaJIO», T. e. B OTKPbITOM Kpyre Iz; |
11 < 1, HJIH Iz - |
11 < 2. |
||
OTCIO,ll.a |
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1 z - 1 |
(z - l)n |
~ (z - l)n |
||
= 2 + ~ + ... + |
2n +1 + ... = ~ 2n +1 |
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, |
... |
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' n=O |
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npaBH.nbHaH 1.faCTb |
• |
|||
06JIacTb CXO,ll.HMOCTH - OTKPbITblit Kpyr Iz - |
11 < 2. |
|||
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469
