Question 115531
help factoring x4 + x2y2 + y4 
= x^4 + 2x^2y^2 + y^4 - x^2y^2

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

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

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Cheers,
Stan H.