求解微分方程:[x-ycos(y/x)]dx+xcos(y/x)dy=0.

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求解微分方程:[x-ycos(y/x)]dx+xcos(y/x)dy=0.
求解微分方程:[x-ycos(y/x)]dx+xcos(y/x)dy=0.

求解微分方程:[x-ycos(y/x)]dx+xcos(y/x)dy=0.
1-y/x*cos(y/x)+cos(y/x)dy/dx=0
令y/x=u,则dy/dx=u+xdu/dx
所以1-ucosu+cosu*(u+xdu/dx)=0
cosu*xdu/dx=-1
cosudu=-dx/x
两边积分:sinu=-ln|x|+C
u=y/x=arcsin(-ln|x|+C)
y=xarcsin(-ln|x|+C)