Question 935134

{{{(x^2+y^2)^2-4x^2y^2}}}

{{{(x^4+2x^2y^2+y^4)-4x^2y^2}}}

{{{x^4+2x^2y^2+y^4-4x^2y^2}}}

{{{x^4-2x^2y^2+y^4}}}

{{{(x^2-y^2)^2}}}

{{{(x^2-y^2)(x^2-y^2)}}}

{{{(x-y)(x+y)(x-y)(x+y)}}}