complete the proof of the polynomial identity.

(x^2+y^2)^2+2x^2y^2-y^4=x^2(x^2+4y^2)

 

\((x^2+y^2)^2+2x^2y^2-y^4=x^2(x^2+4y^2)\\ \)

\(LHS\\=x^4+y^4+2x^2y^2+2x^2y^2-y^4\\ =x^4+4x^2y^2\\ =x^2(x^2+4y^2)\\ =RHS\\~\\ QED\)