How to find the general solution for x(x2+y2)dydx=y(y2x2) using homogeneous ?

1 Answer
May 23, 2018

y=Bxe[y22x2]

Explanation:

x[x2+y2]dydx=y[y2x2], dydx=y3yx2x3+y2.......[1]

Dividing numerator and denominator on the right hand side of .....[1] by x3 and substituting v=yx will give a homogeneous equation in v of the form.......

dydx=v3v1+v2 . From v=yx, y=vx.......[2]

Differentiating.....[2] w.r.t x [implicitly], dydx=xdvdx+v and sustituting for dydx we obtain,

xdvdx = v3v1+v2v, i.e, xdvdx=2v1+v2 which will yield

dxx=1+v22vdv , therefore, dxx=[12v+v22v]dv.

Integrating both sides, lnx=12lnv+v24+C and multiplying both sides by 2 and let C =lnA will give,

lnx2=lnv+v22+lnA, tidying up, ln[Ax2v]=v22,

Ax2v = e[v22][ where 1A is equal to another constant B given in the answer ] and so,

Substituting back for v=yx, we will obtain the answer given above. I hope this was both helpful and correct, and will ask for it to be checked.