题目应是 x^2*ydx=(1-y^2+x^2-x^2y^2)dy 吧。
x^2*ydx=(1-y^2+x^2-x^2y^2)dy 即 x^2*ydx=(1+x^2)(1-y^2)dy ,
则 [(1-y^2)/y]dy = [x^2/(1+x^2)]dx, 即 (1/y-y)dy = [1-1/(1+x^2)]dx,
lny-y^2/2 = x-arctanx +C.
题目应是 x^2*ydx=(1-y^2+x^2-x^2y^2)dy 吧。
x^2*ydx=(1-y^2+x^2-x^2y^2)dy 即 x^2*ydx=(1+x^2)(1-y^2)dy ,
则 [(1-y^2)/y]dy = [x^2/(1+x^2)]dx, 即 (1/y-y)dy = [1-1/(1+x^2)]dx,
lny-y^2/2 = x-arctanx +C.