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求微分方程(x-1)y’=y(1+2xy)的通解
为凑微分,两边同除以y², 得
y'(x-1)/y²=(1+2xy)/y
(dy/dx)(x-1)/y²=(1+2xy)/y
(x-1)dy/y²=(1+2xy)dx/y
[(x/y²)-(1/y²)]dy=[(1/y)+2x]dx
(x/y²)dy-(1/y²)dy=(1/y)dx+2xdx
-(1/y²)dy-2xdx=(1/y)dx-(x/y²)dy
因为 -(1/y²)dy=1/y, 2xdx=x²,
[x*(1/y)]的微分=dx*1/y+x(-1/y²)dy=(1/y)dx-(x/y²)dy,
所以,有 1/y-x²=x/y+C
所以通解是: x²+x/y-1/y+C=0
为凑微分,两边同除以y², 得
y'(x-1)/y²=(1+2xy)/y
(dy/dx)(x-1)/y²=(1+2xy)/y
(x-1)dy/y²=(1+2xy)dx/y
[(x/y²)-(1/y²)]dy=[(1/y)+2x]dx
(x/y²)dy-(1/y²)dy=(1/y)dx+2xdx
-(1/y²)dy-2xdx=(1/y)dx-(x/y²)dy
因为 -(1/y²)dy=1/y, 2xdx=x²,
[x*(1/y)]的微分=dx*1/y+x(-1/y²)dy=(1/y)dx-(x/y²)dy,
所以,有 1/y-x²=x/y+C
所以通解是: x²+x/y-1/y+C=0
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