答：
(y²-x)dy/dx+y=0
(x-y²)dy/dx=y
dy/dx=y/(x-y²)
dx/dy=(x-y²)/y=x/y-y
x'-x/y=-y
x'/y-x/y²=-1
(yx'-x)/y²=-1
(x/y)'=-1
x/y=-y+C
x=-y²+Cy