How to find the general solution for xy (dy/dx - 1)= x^2 + y^2xy(dydx1)=x2+y2 ?

Homogeneous differential equations

1 Answer
May 20, 2018

y/x=ln|y+x|+Cyx=ln|y+x|+C

Explanation:

Given

xy(y'-1)=x^2+y^2

Rearrange:

y'=1+x/y+y/x

Apply the substitution y(x)=xv(x):

v+xv'=1+1/v+v

Simplify and collect like terms:

v/(v+1)v'=1/x

Form the integral:

int(1-1/(v+1))dv=int1/xdx

Integrate term by term:

v-ln|v+1|=ln|x|+C

Simplify:

v=ln|xv+x|+C

Reverse the substitution:

y/x=ln|y+x|+C