推 smallprawn : 非常感謝!! 10/21 22:05
※ 引述《smallprawn (蝦子)》之銘言:
: 1. y''+siny=0, y(0)=0,y(0)=2
: 2.如下圖
: https://imgur.com/a/FOQSb9k
: 以上兩題煩請高手解題了,謝謝!!
2.
x^2 y_1" + 2x y_1' + (x - 2)y_1 = 0
x^2 y_2" + 2x y_2' + (x - 2)y_2 = 0
=> x^2 [y_2y_1' - y_1y_2']' + 2x[y_2y_1' - y_1y_2'] = 0
=> -x^2 W' - 2xW = 0
=> W = c/x^2
W(1) = -2 = c
=> W = -2/x^2
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