[理工] 拉氏解微方
Solve xy"+2y'+xy = 0
做法：
L[xy"] + 2L[Y'] + L[xy] = 0
-d/ds(s^2Y-cs) + 2(sY-c) + -d/ds(Y) = 0 (let y(0) = c)
整理得
(s^2+1)d/ds(Y) = -c
dY = -c(s^2+1)ds
Y = k1*tan-1(x) + k2
y = k1*1/x(sinx) + k2
但是解答是
k1*1/x(sinx) + k2*1/x(cosx)
請教大家過程哪裡出錯了
麻煩各位!
Thanks
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