I need help factoring quadratics.

Question

I need help factoring $x^4-2x^2-3=0$. I do not know how to factor this disguised quadratic.

Answer 1

HINT

Rewrite $-2x^2$ as $-3x^2+x^2$ and group.

More specifically, $x^4-2x^2-3$ is equivalent to $x^4-3x^2+x^2-3$.

Can you proceed?

Answer 2

take $y=x^2$ hence you have $y^2-2y-3=0$ hance $(y-3)(y+1)=0$