# Math Help - Factor Theorem

1. ## Factor Theorem

Factor x^4 + 4 in Q[x].

I'm not sure how to start this...

2. ## Re: Factor Theorem

\begin{align*}x^4+4 & = x^4+4x^2 - 4x^2 + 4 \\ & = (x^4+4x^2+4) - (2x)^2 \\ & = (x^2+2)^2-(2x)^2 \\ & = (x^2+2x+2)(x^2-2x+2)\end{align*}