/sci/ - Science & Math

>this whole thread
Thank you /sci/ I was feeling a bit stressed with my studies but this really helped me out. Thank you.

Can anyone here help me with writing the partial fraction decomposition of <span class="math">\frac {x^2 + 1}{(x^2 + 4)^2} [/spoiler]?
So far I've ended up with <span class="math">{x^2 + 1}=(Ax+B)(x^2+4)+Cx+D[/spoiler] but I can't figure out how to do it from here.
I've tried making x=-4 to get rid of the A and B but I still end up with 17=-4C + D.