# Thread: Integration by partial fractions

1. ## Integration by partial fractions

Hey, I was wondering if somebody could check over the following integration problem for me.

Int (x^2 + 1 ) / (X^2 - 3x + 2) dx

I used partial fractions (disregard title)

for an answer I got ln absolute value (x-2) - ln absolute value (x-1) + c

gracias !!!!!

edit: i originally thought you did int. by parts, but partial fractions makes more sense.

2. Why is there division in the integral. Do you mean perhaps to say * insteand of /

3. It is written as

integrate: (x^2 + 1 ) (divided by) (X^2 - 3x + 2) dx

If you were talking about why is there a / instead * in relation to my original comment of int. by parts, I wrote down the wrong method. (my bad )

it is indeed supposed to be divided by, sorry for any confusion.

1/(x-2)-1/(x-1)=1/(x^2-3x+2)

Which is clearly wrong.
How did you express it as partial fractions?

5. Why I didn't check it before it beyond me and you are clearly right, the answer doesn't even come close. Upon looking over my work though I think I have found the problem. If you express it as partial fractions from the start, you'll have it set equal to x^2 + 1, but there won't be anything (once you do out the actual fractions) to set the x^2 part equal to. In other words there won't be any variables (A, b etc) to set equal to x^2. I think you actually have to do synthethetc division first, then from that answer you can move forward with partial fractions. I'm going to check that out.