Hi - I have an assignment with a question that is stumping me at the first hurdle.

Express $\displaystyle x^4 - 4x^2 + 16$ in the form

$\displaystyle (x^2 + Ax + B)$$\displaystyle (x^2 +Cx + D)$

where A,B,C & D are real constants.

I just can't see how to get it in this form to complete the rest of the partial fraction question. Any ideas??