A.Math

2007-05-18 3:27 am

If y=cosx/x , prove that (d^2y)/(dx^2)+(2/x)(dy/dx)+y=0

回答 (1)

2007-05-18 3:39 am

✔ 最佳答案

xy = cosx
y + x dy/dx = - sinx
dy/dx + dy/dx + x ( d^2y/dx^2 ) = - cos = -xy
( d^2y/dx^2 ) + 2/x dy/dx + y = 0

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