Find the integral of the function 1x2+6x+5 14ln|x+1x+5|
![Find the integral of the function 1x2+6x+5 14ln|x+1x+5|](/img/relate-questions.png)
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Find the integral of the function 1x2+6x+5
A.
14ln|(x+1)(x+5)|+c
B.
12ln|(x+3)(x−3)|+c
C.
12ln|(x+1)(x+5)|+c
D.
14ln|(x+3)(x−3)|+c
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Right Answer is: A
SOLUTION
∫dxx2+6x+5
When we get an integral of this form we try to express it as perfect square and proceed.
⇒∫dxx2+6x+5=∫dx(x+3)2−4
This integral is of the form ∫dxx2−a2 which will be equal to 12a ln|x−ax+a|+c
⇒∫dx(x+3)2−4=14ln|(x+3)−2(x+3)+2|+c14ln|(x+1)(x+5)|+c