Question

Factorise: -1x^2y^2+x^4-2y^4

Answer 1

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

Answer 2

-x^2y^2(1-x^2+2y^2)

hope this helps