How do you integrate (2x) / (4x^2 + 12x + 9)2x4x2+12x+9 using partial fractions?

1 Answer
Dec 28, 2016

=1/2ln|2x+3|+3/(2(2x+3))+C=12ln|2x+3|+32(2x+3)+C.
You don't use partial fractions, because the denominator is a perfect square.

Explanation:

int (2x)/(4x^2+12x+9)dx2x4x2+12x+9dx
=int(2x)/(2x+3)^2dx=2x(2x+3)2dx
So substitute u=2x+3u=2x+3, dx=(du)/2dx=du2:
=1/2int (u-3)/u^2du=12u3u2du
=1/2intu^-1-3u^-2dx=12u13u2dx
=1/2ln|2x+3|+3/(2(2x+3))+C=12ln|2x+3|+32(2x+3)+C