Question

How do you factor #-x^2y^2 + x^4 + 4y^2 - 4x^2 #?

Answer 1

Combination

Explanation:

We have the equation as

`f(x,y) = -x^2y^2+x^4+4y^2-4x^2`
`= x^4-x^2y^2-4x^2+4y^2`
`= x^2(x^2-y^2)-4(x^2-y^2)`
`= (x^2-y^2)\times (x^2-4)`