Thread: [SOLVED] help partial fractions

hey i need help with this, X^2 + 9x + 8/(X^2 + x - 6)

When I do the polynomial division I get 1 + 8x - 14. But then the answer for the partial fraction turns out all wrong when i check it against the answer giving in the textbook. The answer given in the book is : 1 + 2/(x - 3) + 6/(X + 1). How did they derive this answer? wtf am I doing wrong, its driving me nuts. Thank you.

Originally Posted by walk_in_fark

hey i need help with this, X^2 + 9x + 8/(X^2 + x - 6)

When I do the polynomial division I get 1 + 8x - 14. But then the answer for the partial fraction turns out all wrong when i check it against the answer giving in the textbook. The answer given in the book is : 1 + 2/(x - 3)** + 6/(X + 1)**. How did they derive this answer? What am I doing wrong, its driving me nuts. Thank you.

As you said



Now for the last piece look for a decomposition as follows



multiply by



giving



expanding a group terms depending on whether there's a x or not




Solving for A and B gives A = 2, B = 6 so



although it doesn't agree with what you have in your denominator (above **).

Thanks a lot, I now I know that is a type, again thank you.

Originally Posted by danny arrigo

As you said



Now for the last piece look for a decomposition as follows



multiply by



giving



expanding a group terms depending on whether there's a x or not




Solving for A and B gives A = 2, B = 6 so



although it doesn't agree with what you have in your denominator (above **).

you made an error here. in the red line, you should have . you mixed the signs up. as it stands now, your solutions don't work. a minor mistake. the original poster should take note and fix the error him/herself