Question

How do you factor −x2y2+x4+4y2−4x2?

Answer 1

Trying to find out where the common term (here, x2-y2) is the best way to solve this kind of questions

Answer 2

Solution:

-x²y²+x⁴+4y²-4x²

= (-x²)(y²-x²)+4(y²-x²)

= (y²-x²)(-x²+4)

=(y²-x²)(2²-x²)

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

Therefore,

-x²y²+x⁴+4y²-4x²

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

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