SOLUTION: I couldn't find the proper place to submit this question, because you do not have a pre-calculus section on your website. Hopefully you can still answer this question. (9x^

Algebra ->  Trigonometry-basics -> SOLUTION: I couldn't find the proper place to submit this question, because you do not have a pre-calculus section on your website. Hopefully you can still answer this question. (9x^      Log On


   

Question 395282: I couldn't find the proper place to submit this question, because you do not have a pre-calculus section on your website. Hopefully you can still answer this question.
(9x^2-24x-57)/(x+1)(x+3)(x-5) It's a partial fraction decomposition problem. I haven't done any of these in a while, so I can't remember what to do with (9x^2-24x-57).
Thanks
Answer by jrfrunner(365) About Me  (Show Source):
You can put this solution on YOUR website!
set up the following equation

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next multiply both sides by the common denominator (x+1)(x+3)(x-5)
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%289x%5E2-24x-57%29=A%28x%2B3%29%28x-5%29%2BB%28x%2B1%29%28x-5%29%2BC%28x%2B1%29%28x%2B3%29
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at this point you can expand out all terms, then combined common terms and set correponding parts equal yielding a system of equation to solve for A,B and C
but another alternative is to select "convenient values of x and solve
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x=-1: 9%28-1%29%5E2-24%28-1%29-57=A%28-1%2B3%29%28-1-5%29%2BB%2A0%2BC%2A0
9+24-57=-12A or A=-24/-12=2
x=-3: 9%28-3%29%5E2-24%28-3%29-57=A%2A0%2BB%2A%28-3%2B1%29%28-3-5%29%2BC%2A0
81+72-57=72B or B=96/72=4/3
x=5: 9%285%29%5E2-24%285%29-57=A%2A0%2BB%2A0%2BC%2A%285%2B1%29%285%2B3%29
225-120-57=48C or C=48/48=1
==
if I did my math correctly