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find the integral of (3x^2 -3x+4)/(-x^2 +2x+15)

2007-09-27 14:45:31 · 2 answers · asked by ! 2 in Science & Mathematics Mathematics

2 answers

It's nasty (integrals have a way of being nasty ☺), but break it up into the sum of 3 integrals. I got
-3x -8ln(x-5)+5ln(x+3) +C

Doug

2007-09-27 14:54:00 · answer #1 · answered by doug_donaghue 7 · 0 0

(3x^2 - 3x + 4)/(-x^2 + 2x + 15)

-(3x^2 - 3x + 4)/(x^2 - 2x -15)

-(3x^2 - 3x + 4)/(x+3)(x-5)

splitting into partial fractions

-[(3x + 4)/(x+3) + 8/(x-5)]

-[3(x+3)(x+3) - 4/(x+3) + 8/(x-5)]

-3 ∫dx + 4∫dx/(x+3) dx - 8∫dx(x-5)

-3 x + 4ln(x+3) - 8ln(x-5) +c

2007-09-27 22:21:12 · answer #2 · answered by mohanrao d 7 · 0 0

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