Методические указания по выполнению контрольной работы № 2 по математике для студентов инженерно-технических специальностей заочной формы обучения
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ȼɫɟ ɩɪɨɢɡɜɨɞɧɵɟ yc, ycc,..., y(n) ɜɵɪɚɠɚɸɬɫɹ ɱɟɪɟɡ ɩɪɨɢɡɜɨɞɧɵɟ ɨɬ ɧɨɜɨɣ ɧɟɢɡɜɟɫɬɧɨɣ ɮɭɧɤɰɢɢ z( y) ɩɨ y:
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ɉɨɞɫɬɚɜɢɜ ɷɬɢ |
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ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɟ ɭɪɚɜɧɟɧɢɟ (n 1) –ɝɨ ɩɨɪɹɞɤɚ.
Ɂɚɦɟɱɚɧɢɟ. ɉɪɢ ɪɟɲɟɧɢɢ ɡɚɞɚɱɢ Ʉɨɲɢ: ɧɚɱɚɥɶɧɵɟ ɭɫɥɨɜɢɹ ɥɭɱɲɟ ɢɫɩɨɥɶɡɨɜɚɬɶ ɧɟɩɨɫɪɟɞɫɬɜɟɧɧɨ ɜ ɩɪɨɰɟɫɫɟ ɪɟɲɟɧɢɹ ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɝɨ ɭɪɚɜɧɟɧɢɹ.
ɉɪɢɦɟɪ 4.8. Ɋɟɲɢɬɶ ɡɚɞɚɱɭ Ʉɨɲɢ
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Ɋɟɲɟɧɢɟ. |
Ⱦɚɧɧɨɟ ɭɪɚɜɧɟɧɢɟ |
ɧɟ |
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ɫɨɞɟɪɠɢɬ ɧɟɡɚɜɢɫɢɦɭɸ ɩɟɪɟɦɟɧɧɭɸ, |
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ɩɨɷɬɨɦɭ ɩɨɥɚɝɚɟɦ y |
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z( y) . Ɍɨɝɞɚ y |
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yz dydz z2 y4 .
ɉɭɫɬɶ yz z 0, ɬɨɝɞɚ ɦɵ ɩɨɥɭɱɚɟɦ ɭɪɚɜɧɟɧɢɟ Ȼɟɪɧɭɥɥɢ ɨɬɧɨɫɢɬɟɥɶɧɨ z z( y)
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Ɋɟɲɚɹ ɟɝɨ, ɧɚɯɨɞɢɦ z |
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y2 C1 . ɂɡ ɭɫɥɨɜɢɹ yc |
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ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɟ ɭɪɚɜɧɟɧɢɟ |
ɫ |
ɪɚɡɞɟɥɹɸɳɢɦɢɫɹ |
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C2 . ɉɨɥɚɝɚɹ |
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61
Ɉɫɬɚɥɨɫɶ ɡɚɦɟɬɢɬɶ, ɱɬɨ ɫɥɭɱɚɣ yz 0 ɧɟ ɞɚɟɬ ɪɟɲɟɧɢɣ ɩɨɫɬɚɜɥɟɧɧɨɣ ɡɚɞɚɱɢ Ʉɨɲɢ.
5. ɅɂɇȿɃɇɕȿ ȾɂɎɎȿɊȿɇɐɂȺɅɖɇɕȿ ɍɊȺȼɇȿɇɂə ȼɕɋɒɂɏ ɉɈɊəȾɄɈȼ ɋ ɉɈɋɌɈəɇɇɕɆɂ ɄɈɗɎɎɂɐɂȿɇɌȺɆɂ
5.1. Ʌɢɧɟɣɧɵɟ ɨɞɧɨɪɨɞɧɵɟ ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɵɟ ɭɪɚɜɧɟɧɢɹ n–ɝɨ ɩɨɪɹɞɤɚ ɫ ɩɨɫɬɨɹɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ
Ʌɢɧɟɣɧɨɟ ɨɞɧɨɪɨɞɧɨɟ ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɟ ɭɪɚɜɧɟɧɢɟ n–ɝɨ ɩɨɪɹɞɤɚ ɫ ɩɨɫɬɨɹɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ ɢɦɟɟɬ ɜɢɞ
y(n) a1 y(n 1) a2 y(n 2) ... an 1 yc an y 0 , |
(5.1) |
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ɝɞɟ ai const, |
ai R . |
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Ⱦɥɹ ɧɚɯɨɠɞɟɧɢɹ ɨɛɳɟɝɨ ɪɟɲɟɧɢɹ ɭɪɚɜɧɟɧɢɹ (5.1) ɫɨɫɬɚɜɥɹɟɬɫɹ |
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ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ ɭɪɚɜɧɟɧɢɟ |
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k n a k n 1 a |
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ɢɧɚɯɨɞɹɬɫɹ ɟɝɨ ɤɨɪɧɢ k1 , k2 ,..., kn . ȼɨɡɦɨɠɧɵ ɫɥɟɞɭɸɳɢɟ ɫɥɭɱɚɢ
1.ȼɫɟ ɤɨɪɧɢ k1 , k2 ,..., kn ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ (5.2) ɞɟɣɫɬɜɢɬɟɥɶɧɵ
ɢɪɚɡɥɢɱɧɵ. Ɉɛɳɟɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ (5.1) ɜɵɪɚɠɚɟɬɫɹ ɮɨɪɦɭɥɨɣ
(5.3)
2. ɏɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ ɭɪɚɜɧɟɧɢɟ ɢɦɟɟɬ ɩɚɪɭ ɨɞɧɨɤɪɚɬɧɵɯ ɤɨɦɩɥɟɤɫɧɨ– DrEi . ȼ ɮɨɪɦɭɥɟ (5.3) ɫɨɨɬɜɟɬɫɬɜɭɸɳɚɹ ɩɚɪɚ ɱɥɟɧɨɜ
C ek1x C |
ek2 x |
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eDx (C cosEx C |
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3. Ⱦɟɣɫɬɜɢɬɟɥɶɧɵɣ ɤɨɪɟɧɶ k1 ɭɪɚɜɧɟɧɢɹ |
(5.2) |
ɢɦɟɟɬ |
ɤɪɚɬɧɨɫɬɶ |
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r (k |
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) . Ɍɨɝɞɚ ɫɨɨɬɜɟɬɫɬɜɭɸɳɢɟ r ɱɥɟɧɨɜ |
C ek1x ... C |
ekr x |
ɜ ɮɨɪɦɭɥɟ |
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(5.3) ɡɚɦɟɧɹɸɬɫɹ ɫɥɚɝɚɟɦɵɦ
62
ek1x (C1 C2 x C3 x2 ... Cr xr 1 ) .
4. ɉɚɪɚ ɤɨɦɩɥɟɤɫɧɨ–ɫɨɩɪɹɠɟɧɧɵɯ ɤɨɪɧɟɣ k1,2 DrEi ɭɪɚɜɧɟɧɢɹ (5.2) ɢɦɟɟɬ
ɤɪɚɬɧɨɫɬɶ r. ȼ ɷɬɨɦ ɫɥɭɱɚɟ ɫɨɨɬɜɟɬɫɬɜɭɸɳɢɟ r ɩɚɪ ɱɥɟɧɨɜ C1ek1x ... C2rek2 r x ɜ
ɮɨɪɦɭɥɟ (5.3) ɡɚɦɟɧɹɸɬɫɹ ɫɥɚɝɚɟɦɵɦ
eDx [(C C |
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x ... C |
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xr 1 ) cosEx (C |
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C |
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x ... C |
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xr 1 )sinEx] . |
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ɉɪɢɦɟɪ |
5.1. Ɋɟɲɢɬɶ |
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y IV 5ycc 4 y 0 . |
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ɭɪɚɜɧɟɧɢɟ k 4 5k 2 4 |
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ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɝɨ ɭɪɚɜɧɟɧɢɹ
y C1e x C2e x C3e2 x C4e 2 x .
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5.2. |
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ɭɪɚɜɧɟɧɢɟ ycc 2 yc 5y |
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ɭɪɚɜɧɟɧɢɟ k 2 2k 5 |
0 ɢɦɟɟɬ ɤɨɪɧɢ k |
1 r 2i . Ɉɛɳɟɟ ɪɟɲɟɧɢɟ ɢɦɟɟɬ ɜɢɞ |
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5.3. |
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ɭɪɚɜɧɟɧɢɟ |
ycc 2 yc y |
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ɭɪɚɜɧɟɧɢɟ |
k 2 2k 1 0 |
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1, ɩɨɷɬɨɦɭ ɨɛɳɟɟ |
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e x (C |
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ɉɪɢɦɟɪ 5.4. Ɋɟɲɢɬɶ |
ɭɪɚɜɧɟɧɢɟ y IV |
8 yccc 16 yc |
0 . ɏɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ |
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ɭɪɚɜɧɟɧɢɟ |
k 5 8k 3 16k |
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k4,5 2i . Ɉɛɳɟɟ |
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ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ ɬɚɤɨɜɨ |
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C1 C2 cos 2x C3 sin 2x C4 x cos 2x C5 x sin 2x . |
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63
5.2.Ʌɢɧɟɣɧɵɟ ɧɟɨɞɧɨɪɨɞɧɵɟ ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɵɟ ɭɪɚɜɧɟɧɢɹ
ɫɩɨɫɬɨɹɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ
Ʌɢɧɟɣɧɨɟ ɧɟɨɞɧɨɪɨɞɧɨɟ ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɟ ɭɪɚɜɧɟɧɢɟ ɫ ɩɨɫɬɨɹɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ ɢɦɟɟɬ ɜɢɞ
y(n) |
a1 y(n 1) ... an 1 yc an y f ( x) , |
(5.4) |
ɝɞɟ ai R, |
f ( x) – ɧɟɩɪɟɪɵɜɧɚɹ ɮɭɧɤɰɢɹ. |
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y C1 y1 C2 y2 ... Cn yn – |
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– ɨɛɳɟɟ ɪɟɲɟɧɢɟ ɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ (5.1), ɫɨɨɬɜɟɬɫɬɜɭɸɳɟɝɨ ɭɪɚɜɧɟɧɢɸ (5.4). Ɇɟɬɨɞ ɜɚɪɢɚɰɢɢ ɩɪɨɢɡɜɨɥɶɧɵɯ ɩɨɫɬɨɹɧɧɵɯ ɫɨɫɬɨɢɬ ɜ ɬɨɦ, ɱɬɨ ɨɛɳɟɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ (5.4) ɢɳɟɬɫɹ ɜ ɜɢɞɟ
y C1 (x) y1 C2 ( x) y2 ... Cn ( x) yn ,
ɝɞɟ C1(x),..., Cn (x) – ɧɟɢɡɜɟɫɬɧɵɟ ɮɭɧɤɰɢɢ. ɗɬɢ ɮɭɧɤɰɢɢ ɨɩɪɟɞɟɥɹɸɬɫɹ ɢɡ ɫɢɫɬɟɦɵ
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C1c(x) y1 C2c (x) y2 |
Cnc (x) yn |
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ɝɞɟ |
Cic |
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dCi (x) |
– ɩɪɨɢɡɜɨɞɧɵɟ ɮɭɧɤɰɢɣ Ci |
( x) . Ⱦɥɹ ɭɪɚɜɧɟɧɢɹ ɜɬɨɪɨɝɨ ɩɨɪɹɞɤɚ |
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ycc p x yc q x y |
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ɞɚɧɧɚɹ ɫɢɫɬɟɦɚ ɢɦɟɟɬ ɜɢɞ |
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ɉɪɢɦɟɪ 5.5. Ɋɟɲɢɬɶ ɭɪɚɜɧɟɧɢɟ ycc yc |
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64
Ɋɟɲɟɧɢɟ. ɏɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ ɭɪɚɜɧɟɧɢɟ ɢɦɟɟɬ ɤɨɪɧɢ k1
ɉɨɷɬɨɦɭ |
ɨɛɳɟɟ ɪɟɲɟɧɢɟ |
ɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ ɛɭɞɟɬ ɬɚɤɢɦ: y |
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ɉɨɥɨɠɢɦ C1 |
C1 ( x) ɢ C2 |
C2 (x) . Ɂɚɩɢɲɟɦ ɫɢɫɬɟɦɭ ɞɥɹ ɨɩɪɟɞɟɥɟɧɢɹ |
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ɢ C2c C2c ( x) : |
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0, k2 1.
C1 C2ex . C1c C1c(x)
Ɋɟɲɚɹ ɷɬɭ ɫɢɫɬɟɦɭ ɭɪɚɜɧɟɧɢɣ, ɩɨɥɭɱɚɟɦ:
C2c (x)
ɨɬɫɸɞɚ
C1(x)
C2 (x)
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e x x ln | ex 1| C2 , |
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ɝɞɟ C1 |
C2 |
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Ɉɛɳɟɟ ɪɟɲɟɧɢɟ ɡɚɩɢɲɟɬɫɹ ɬɚɤ: |
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6. ɅɂɇȿɃɇɕȿ ɇȿɈȾɇɈɊɈȾɇɕȿ ȾɂɎɎȿɊȿɇɐɂȺɅɖɇɕȿ ɍɊȺȼɇȿɇɂə ȼɕɋɒɂɏ ɉɈɊəȾɄɈȼ ɋ ɉɈɋɌɈəɇɇɕɆɂ ɄɈɗɎɎɂɐɂȿɇɌȺɆɂ ɂ ɋɉȿɐɂȺɅɖɇɈɃ ɉɊȺȼɈɃ ɑȺɋɌɖɘ
Ɋɚɫɫɦɨɬɪɢɦ ɧɟɨɞɧɨɪɨɞɧɨɟ ɞɢɮɮɟɪɟɧɰɢɚɥɶɧɨɟ ɭɪɚɜɧɟɧɢɟ n–ɝɨ ɩɨɪɹɞɤɚ ɫ ɩɨɫɬɨɹɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ
65
L( y) { y(n) |
a y(n 1) |
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f (x) , |
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ɮɭɧɤɰɢɹ. |
ɋɨɨɬɜɟɬɫɬɜɭɸɳɢɦ ɨɞɧɨɪɨɞɧɵɦ |
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ɭɪɚɜɧɟɧɢɟɦ ɛɭɞɟɬ |
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y(n) a y(n 1) |
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ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ ɭɪɚɜɧɟɧɢɟ ɞɥɹ ɭɪɚɜɧɟɧɢɹ (6.2). Ɉɛɳɟɟ ɪɟɲɟɧɢɟ y ɭɪɚɜɧɟɧɢɹ (6.1) ɪɚɜɧɨ ɫɭɦɦɟ ɨɛɳɟɝɨ ɪɟɲɟɧɢɹ y ɫɨɨɬɜɟɬɫɬɜɭɸɳɟɝɨ ɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ
(6.2) ɢ ɤɚɤɨɝɨ–ɥɢɛɨ ɱɚɫɬɧɨɝɨ ɪɟɲɟɧɢɹ y * ɧɟɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ (6.1), ɬɨ ɟɫɬɶ
y |
y y *. |
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ȿɫɥɢ |
ɩɪɚɜɚɹ |
ɱɚɫɬɶ ɭɪɚɜɧɟɧɢɹ (6.1) |
ɢɦɟɟɬ ɜɢɞ: |
f (x) P ( x)eDx , |
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ɝɞɟ Pn (x) |
–ɦɧɨɝɨɱɥɟɧ ɫɬɟɩɟɧɢ n, ɬɨ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ (6.1) ɦɨɠɟɬ ɛɵɬɶ |
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ɧɚɣɞɟɧɨ ɜ ɜɢɞɟ: |
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ɝɞɟ Q(x) A xn A xn 1 ... A |
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ɦɧɨɝɨɱɥɟɧ |
ɫɬɟɩɟɧɢ n ɫ |
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ɧɟɨɩɪɟɞɟɥɟɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ, ɚ r – ɱɢɫɥɨ, ɩɨɤɚɡɵɜɚɸɳɟɟ ɫɤɨɥɶɤɨ ɪɚɡ D ɹɜɥɹɟɬɫɹ ɤɨɪɧɟɦ ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ.
ɉɪɢɦɟɪ 6.1. ɇɚɣɬɢ ɨɛɳɟɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ ycc y |
xe2 x . |
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Ɋɟɲɟɧɢɟ. ɋɨɫɬɚɜɥɹɟɦ ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ ɭɪɚɜɧɟɧɢɟ |
k 2 1 |
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ɫɨɨɬɜɟɬɫɬɜɭɸɳɟɝɨ ɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ. ȿɝɨ ɤɨɪɧɢ |
k1 1, k2 |
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Ɍɚɤ |
ɤɚɤ |
ɱɢɫɥɨ D 2 ɤɨɪɧɟɦ ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ ɧɟ ɹɜɥɹɟɬɫɹ, ɬɨ r 0 |
. ɋɬɟɩɟɧɶ |
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ɦɧɨɝɨɱɥɟɧɚ ɜ ɩɪɚɜɨɣ ɱɚɫɬɢ ɪɚɜɧɚ ɟɞɢɧɢɰɟ. ɉɨɷɬɨɦɭ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ ɢɳɟɦ ɜ ɜɢɞɟ y* (ax b)e2 x .
66
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yc (2ax 2b a)e2 x , |
ycc (4ax 4b 4a)e2 x |
ɢ, ɩɨɞɫɬɚɜɥɹɹ ycc, |
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ycɢ y ɜ ɭɪɚɜɧɟɧɢɟ, ɩɨɥɭɱɢɦ (ɩɨɫɥɟ ɫɨɤɪɚɳɟɧɢɹ ɧɚ e2 x ) |
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4a 4ax 4b ax b x . |
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Ɉɬɤɭɞɚ ɧɚɯɨɞɢɦ: |
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ɚ ɨɛɳɟɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ ɛɭɞɟɬ |
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y C ex C |
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2) ȿɫɥɢ ɩɪɚɜɚɹ ɱɚɫɬɶ ɭɪɚɜɧɟɧɢɹ (6.1) ɢɦɟɟɬ ɜɢɞ |
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eDx (P (x) cosEx Q |
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( x) sinEx) , |
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ɝɞɟ Pn (x) ɢ Qm (x) – ɦɧɨɝɨɱɥɟɧɵ n–ɣ ɢ m–ɣ ɫɬɟɩɟɧɢ ɫɨɨɬɜɟɬɫɬɜɟɧɧɨ, ɬɨɝɞɚ: |
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ɚ) ɟɫɥɢ ɱɢɫɥɚ DriE ɧɟ ɹɜɥɹɸɬɫɹ ɤɨɪɧɹɦɢ ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ |
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(6.3), ɬɨ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ (6.1) ɢɳɟɬɫɹ ɜ ɜɢɞɟ |
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eDx (uS ( x) cosEx vS ( x)sinEx) , |
(6.5) |
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ɝɞɟ |
us ɢ |
vs |
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ɦɧɨɝɨɱɥɟɧɵ ɫɬɟɩɟɧɢ s |
ɫ ɧɟɨɩɪɟɞɟɥɟɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ ɢ |
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max{n,m}; |
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ɛ) ɟɫɥɢ ɱɢɫɥɚ DriE ɹɜɥɹɸɬɫɹ ɤɨɪɧɹɦɢ ɤɪɚɬɧɨɫɬɢ r |
ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ |
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ɭɪɚɜɧɟɧɢɹ (6.3), ɬɨ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ (6.1) ɢɳɟɬɫɹ ɜ ɜɢɞɟ |
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xreDx (us (x)cosEx vs (x)sinEx) , |
(6.6) |
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us ɢ |
vs |
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ɦɧɨɝɨɱɥɟɧɵ ɫɬɟɩɟɧɢ s |
ɫ ɧɟɨɩɪɟɞɟɥɟɧɧɵɦɢ ɤɨɷɮɮɢɰɢɟɧɬɚɦɢ ɢ |
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max{n,m}. |
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Ɂɚɦɟɱɚɧɢɹ.
67
1. |
ȿɫɥɢ ɜ (6.4) |
P (x) { 0 |
ɢɥɢ |
Q |
m |
(x) { 0 , |
ɬɨ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ |
y ɬɚɤɠɟ |
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ɢɳɟɬɫɹ ɜ ɜɢɞɟ (6.5), (6.6), ɝɞɟ s |
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m (ɢɥɢ s |
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2. ȿɫɥɢ ɭɪɚɜɧɟɧɢɟ (6.1) ɢɦɟɟɬ ɜɢɞ L( y) |
f1 (x) f2 (x) , ɬɨ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ |
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y ɬɚɤɨɝɨ |
ɭɪɚɜɧɟɧɢɹ |
ɦɨɠɧɨ |
ɢɫɤɚɬɶ |
ɜ |
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y y |
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– ɱɚɫɬɧɨɟ |
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L( y) |
f1 (x) , |
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ɪɟɲɟɧɢɟ |
ɭɪɚɜɧɟɧɢɹ |
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L( y) |
f2 ( x) . |
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ɉɪɢɦɟɪ 6.2. ɇɚɣɬɢ ɨɛɳɟɟ ɪɟɲɟɧɢɟ ɭɪɚɜɧɟɧɢɹ |
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ycc yc ex e2 x x . |
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Ɋɟɲɟɧɢɟ. ɋɨɨɬɜɟɬɫɬɜɭɸɳɟɟ ɨɞɧɨɪɨɞɧɨɟ ɭɪɚɜɧɟɧɢɟ ɢɦɟɟɬ ɜɢɞ |
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ycc yc |
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ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ ɭɪɚɜɧɟɧɢɟ |
k 2 k |
0 |
ɢɦɟɟɬ |
ɤɨɪɧɢ |
k1 |
0, |
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1. Ɉɛɳɟɟ |
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ɪɟɲɟɧɢɟ ɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ: |
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y |
C C |
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e x . |
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ɉɪɚɜɚɹ ɱɚɫɬɶ ɞɚɧɧɨɝɨ ɭɪɚɜɧɟɧɢɹ ɟɫɬɶ ɫɭɦɦɚ |
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f ( x) |
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f1 (x) f2 ( x) f3 (x) |
e x e2 x x . |
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ɉɨɷɬɨɦɭ ɧɚɯɨɞɢɦ ɱɚɫɬɧɵɟ ɪɟɲɟɧɢɹ ɞɥɹ ɤɚɠɞɨɝɨ ɢɡ ɬɪɟɯ ɭɪɚɜɧɟɧɢɣ:
ycc yc ex ; ycc yc e2x ; |
ycc yc x . |
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ɑɚɫɬɧɨɟ ɪɟɲɟɧɢɟ ɩɟɪɜɨɝɨ ɭɪɚɜɧɟɧɢɹ ɢɳɟɦ ɜ ɜɢɞɟ |
y |
Axex , ɬɚɤ ɤɚɤ D |
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ɹɜɥɹɟɬɫɹ |
ɨɞɧɨɤɪɚɬɧɵɦ |
ɤɨɪɧɟɦ |
ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ |
ɢ Pn ( x) 1 |
– |
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ɦɧɨɝɨɱɥɟɧ ɧɭɥɟɜɨɣ ɫɬɟɩɟɧɢ. ɉɨɫɤɨɥɶɤɭ |
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y c |
Aex Axex ; |
y s |
Aex Aex Axex |
2Aex Axex , |
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ɬɨ, ɩɨɞɫɬɚɜɥɹɹ ɷɬɢ ɜɵɪɚɠɟɧɢɹ ɜ ɩɟɪɜɨɟ ɭɪɚɜɧɟɧɢɟ, ɢɦɟɟɦ |
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2 Ae x Axe x Ae x Axe x |
e x ɢɥɢ Aex ex |
A |
1 ɢ |
y |
xex . |
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68
ɑɚɫɬɧɨɟ ɪɟɲɟɧɢɟ ɜɬɨɪɨɝɨ ɭɪɚɜɧɟɧɢɹ ɛɭɞɟɦ ɧɚɯɨɞɢɬɶ ɜ ɜɢɞɟ |
y2 |
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Ae2x , ɬɚɤ |
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ɤɚɤ ɜ ɩɪɚɜɨɣ ɱɚɫɬɢ ɜɬɨɪɨɝɨ |
ɭɪɚɜɧɟɧɢɹ |
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D |
2 |
ɧɟ |
ɹɜɥɹɟɬɫɹ |
ɤɨɪɧɟɦ |
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ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ ɢ Pn (x) |
1 – ɦɧɨɝɨɱɥɟɧ ɧɭɥɟɜɨɣ ɫɬɟɩɟɧɢ. |
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Ɉɩɪɟɞɟɥɹɹ, |
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ɤɚɤ |
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ɢ ɜɵɲɟ, |
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ɩɨɫɬɨɹɧɧɭɸ A, |
ɩɨɥɭɱɢɦ |
y2 |
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e |
2x |
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ɑɚɫɬɧɨɟ |
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ɪɟɲɟɧɢɟ ɬɪɟɬɶɟɝɨ ɭɪɚɜɧɟɧɢɹ ɛɭɞɟɦ ɧɚɯɨɞɢɬɶ ɜ ɜɢɞɟ |
y3* |
x(Ax B) , |
ɬɚɤ ɤɚɤ ɜ |
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ɩɪɚɜɨɣ ɱɚɫɬɢ ɬɪɟɬɶɟɝɨ ɭɪɚɜɧɟɧɢɹ D 0 ɹɜɥɹɟɬɫɹ ɨɞɧɨɤɪɚɬɧɵɦ ɤɨɪɧɟɦ |
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ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ |
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ɭɪɚɜɧɟɧɢɹ |
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ɢ |
Pn ( x) x |
– ɦɧɨɝɨɱɥɟɧ ɩɟɪɜɨɣ ɫɬɟɩɟɧɢ. |
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ɉɨɫɤɨɥɶɤɭ y3 c |
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2Ax B, |
y3 s |
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2A, ɬɨ, |
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ɩɨɞɫɬɚɜɥɹɹ |
ɷɬɢ |
ɜɵɪɚɠɟɧɢɹ |
ɜ ɬɪɟɬɶɟ |
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ɭɪɚɜɧɟɧɢɟ, ɢɦɟɟɦ |
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2 A 2 Ax B B |
x . ɉɪɢɪɚɜɧɢɜɚɹ ɤɨɷɮɮɢɰɢɟɧɬɵ ɩɪɢ x ɢ |
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ɫɜɨɛɨɞɧɵɟ |
ɱɥɟɧɵ |
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ɜ |
ɥɟɜɨɣ ɢ |
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ɩɪɚɜɨɣ |
ɱɚɫɬɹɯ |
ɪɚɜɟɧɫɬɜɚ, ɩɨɥɭɱɚɟɦ ɫɢɫɬɟɦɭ – |
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2 A 1, |
BA B |
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0 , ɨɬɤɭɞɚ ɧɚɯɨɞɢɦ A |
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B |
1. |
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ɋɥɟɞɨɜɚɬɟɥɶɧɨ, |
y3 |
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x¨ |
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x 1¸. |
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©2 |
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¹ |
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ɋɭɦɦɢɪɭɹ |
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ɱɚɫɬɧɵɟ |
ɪɟɲɟɧɢɹ, |
ɩɨɥɭɱɚɟɦ |
ɱɚɫɬɧɨɟ |
ɪɟɲɟɧɢɟ |
y |
ɢɫɯɨɞɧɨɝɨ |
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ɭɪɚɜɧɟɧɢɹ |
y |
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y |
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xex |
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§1 |
x |
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e2x x¨ |
1¸. Ɍɨɝɞɚ ɨɛɳɟɟ ɪɟɲɟɧɢɟ ɞɚɧɧɨɝɨ |
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©2 |
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¹ |
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ɧɟɨɞɧɨɪɨɞɧɨɝɨ ɭɪɚɜɧɟɧɢɹ ɛɭɞɟɬ |
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y y y C C |
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ex xex |
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e2x |
§1 |
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x¨ |
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1¸ |
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C (C |
2 |
x)ex |
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e2x |
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x2 x. |
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ɉɪɢɦɟɪ |
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6.3. |
ɇɚɣɬɢ |
ɱɚɫɬɧɨɟ |
ɪɟɲɟɧɢɟ |
ɭɪɚɜɧɟɧɢɹ |
ycc y |
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4x cos x , |
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ɭɞɨɜɥɟɬɜɨɪɹɸɳɟɟ ɧɚɱɚɥɶɧɵɦ ɭɫɥɨɜɢɹɦ y(0) |
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0, |
c |
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1. |
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y (0) |
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69
Ɋɟɲɟɧɢɟ. ɏɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɟ |
ɭɪɚɜɧɟɧɢɟ |
k 2 1 0 |
ɢɦɟɟɬ |
ɤɨɪɧɢ |
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k1 i, k2 |
i . |
ɉɨɷɬɨɦɭ |
ɨɛɳɢɦ |
ɪɟɲɟɧɢɟɦ |
ɫɨɨɬɜɟɬɫɬɜɭɸɳɟɝɨ |
ɨɞɧɨɪɨɞɧɨɝɨ |
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ɭɪɚɜɧɟɧɢɹ |
ycc y |
0 |
ɛɭɞɟɬ y C1 cos x C2 sin x . |
Ⱦɥɹ |
ɩɟɪɜɨɣ ɱɚɫɬɢ |
ɞɚɧɧɨɝɨ |
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ɭɪɚɜɧɟɧɢɹ |
D |
0, |
E |
1, |
Pn ( x) 4x – ɦɧɨɝɨɱɥɟɧ |
ɩɟɪɜɨɣ |
ɫɬɟɩɟɧɢ; |
(n |
1), |
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Qm ( x) 0 |
– ɦɧɨɝɨɱɥɟɧ |
ɧɭɥɟɜɨɣ |
ɫɬɟɩɟɧɢ |
(m |
0) ; |
s |
max{1,0} |
1, DiE |
i |
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ɹɜɥɹɸɬɫɹ ɤɨɪɧɹɦɢ ɯɚɪɚɤɬɟɪɢɫɬɢɱɟɫɤɨɝɨ ɭɪɚɜɧɟɧɢɹ. ɉɨɷɬɨɦɭ ɱɚɫɬɧɨɟ ɪɟɲɟɧɢɟ
ɞɚɧɧɨɝɨ |
ɭɪɚɜɧɟɧɢɹ ɧɚɯɨɞɢɦ ɜ ɜɢɞɟ y x(( Ax B)cos x (Cx D)sin x) ɢɥɢ |
y ( Ax2 Bx) cos x (Cx2 Dx)sin x . |
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ɇɚɯɨɞɢɦ |
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y c |
(2Ax B)cos x (2Cx D)sin x |
( Ax2 Bx)sin x (Cx2 Dx)cos x |
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(2Ax B C 2 Dx)cos x (2Cx D Ax2 Bx)sin x; |
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y cc |
(2A 2Cx D)cos x (2Ax B Cx2 Dx)sin x |
(2C 2Ax B)sin x (2Cx D Ax2 Bx)cos x
(2A 4Cx 2D Ax2 Bx)cos x (2C 4Ax 2B Cx2 Dx)sin x.
ɉɨɞɫɬɚɜɥɹɹ ɜ ɞɚɧɧɨɟ ɭɪɚɜɧɟɧɢɟ, ɢɦɟɟɦ
(2 A 2 ACx 2D Ax2 Bx) cos x (2C 4Ax 2B Cx2 Dx) u
usin x ( Ax2 Bx) cos x (Cx2 Dx)sin x |
4x cos x. |
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ɉɪɢɪɚɜɧɢɜɚɹ ɤɨɷɮɮɢɰɢɟɧɬɵ ɩɪɢ cos x, sin x, x cos x, x sin x ɜ ɨɛɟɢɯ ɱɚɫɬɹɯ |
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ɪɚɜɟɧɫɬɜɚ, ɩɨɥɭɱɚɟɦ ɫɢɫɬɟɦɭ |
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cos x |
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2A 2D |
0; |
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sin 0 x |
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2C 2B |
0; |
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x cos x |
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4C B B |
4; |
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x sin x |
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4A D D |
0. |
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Ɋɟɲɚɹ ɷɬɭ ɫɢɫɬɟɦɭ, ɧɚɯɨɞɢɦ A 0, B 1, C 1, D |
0 . Ɍɨɝɞɚ |
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70
