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Calculus problem:


\int\limits_ } \, (9x+2)/(x^2+x-6) dx
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User Kalle Richter
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2 Answers

9 votes
9 votes
Don’t think it’s possible
User Freddieptf
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Split the integrand into partial fractions.


(9x+2)/(x^2+x-6) = (9x+2)/((x-2)(x+3)) = \frac a{x-2} + \frac b{x+3}


\implies 9x+2 = a(x+3) + b(x-2) = (a+b)x + (3a-2b)


\implies \begin{cases}a+b=9 \\ 3a-2b=2\end{cases} \implies a=4,b=5

Then we have


\displaystyle \int (9x+2)/(x^2+x-6) \, dx = 4 \int (dx)/(x-2) + 5 \int (dx)/(x+3) \\\\ = \boxed + 5\ln

which follows from the result


\displaystyle \int \frac{dx}x = \ln|x|+C

User John Burger
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