Stuck on partial fraction question

sinclairharry

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Mar 22, 2015
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Question is

\(\displaystyle \int \frac{2x^2-3x-12}{\left(2x-1\right)\left(x^2+3\right)}dx\)

and then i would apply the sub intergral rule so

\(\displaystyle =\int \frac{x\left(2x-3\right)-12}{2\left(x^2+3\right)u}du\)

\(\displaystyle \frac{1}{2}\int \frac{6\left(u+1\right)}{u\left(u+2\right)+13}-\frac{4}{u}du\)

and then to apply the sum rule to get

\(\displaystyle =\frac{1}{2}\left(3\ln \left(u\left(u+2\right)+13\right)-4\ln \left(u\right)\right)\)

meaning my answer was

\(\displaystyle =\frac{3\ln \left(\left(2x-1\right)\left(2x+1\right)+13\right)-4\ln \left(2x-1\right)}{2}+C\)

but it seems to be incorrect can anyone point out my error ?

cheers
 
Last edited by a moderator:
Question is

\(\displaystyle \int \frac{2x^2-3x-12}{\left(2x-1\right)\left(x^2+3\right)}dx\)

and then i would apply the sub intergral rule so

\(\displaystyle =\int \frac{x\left(2x-3\right)-12}{2\left(x^2+3\right)u}du\)

\(\displaystyle \frac{1}{2}\int \frac{6\left(u+1\right)}{u\left(u+2\right)+13}-\frac{4}{u}du\)

and then to apply the sum rule to get

\(\displaystyle =\frac{1}{2}\left(3\ln \left(u\left(u+2\right)+13\right)-4\ln \left(u\right)\right)\)

meaning my answer was

\(\displaystyle =\frac{3\ln \left(\left(2x-1\right)\left(2x+1\right)+13\right)-4\ln \left(2x-1\right)}{2}+C\)

but it seems to be incorrect can anyone point out my error ?

cheers

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