Use partial fractions:
∫(x−7)/(x^2−x−12)dx

Question

Use partial fractions: 
∫(x−7)/(x^2−x−12)dx

anonymous · Answer

I got AX +3A +BX -4B = X-7
I solved and got A=-3/7 and B =10/7
which gave me $$\frac{ -3 }{ 7 }\ln(x-4)+\frac{ 10 }{ 7 } \ln(x+3)$$
Anyone know where I went wrong?

loser66 · Answer

why do you think it is wrong?

hartnn · Answer

you just missed the "+c" part after integration, everything else is correct.

anonymous · Answer

webworks says I got it incorrect, I attached a screenshot.  Could you guys check to see if it looks right?

hartnn · Answer

please add the "+c" in your answer and check again

hartnn · Answer

i see its already there...

anonymous · Answer

If I add the +c, I get "Variable 'C' is not defined in this context"

loser66 · Answer

you have the option "email instructor" :)
I don't see anything wrong.

hartnn · Answer

ln(4-x)
instead of ln(x-4)

anonymous · Answer

http://www.wolframalpha.com/input/?i=%28x%E2%88%927%29%2F%28x^2%E2%88%92x%E2%88%9212%29

anonymous · Answer

Thank you.  I feel stupid

loser66 · Answer

@ryanmk54  I am with you. :) don't know why ln (4-x)

loser66 · Answer

If you say ln |x-4| , I am ok

anonymous · Answer

I see what you are saying now.  Absolute value of x-4 = Absolute value -x+4