Factor the expression x^4 + 6x^2 - 7 completely.

So since the first x is raised to the 4th power and the second is raised to the 2nd power and the last number is a negative, you automatically start your factor with (x^2+__) (x^2-__) Then you have to look at factors that would multiply to make - 7 and add to make 6, which would be + 7 and - 1 so you end up with (x^2+7) (x^2-1)