Given differential equation is 2x4ydxdy+y4=4x4,
Substituting y=un
⟹dxdy=nun−1dxdu gives,
⟹2x4un(nun−1dxdu)=4x4−u4n⟹dxdu=nu2n−12−2nx4u2n+1,
Given this equation is homogenous,
By inspection,if n=21,
The equation becomes dxdu+x4u2=4, which is homogenous.