Evaluate the following integral:

Let substitute
, so the given equation becomes
![]()
Factorizing the denominator, we get
![]()
The denominator is factorized, so let separate the fraction through partial fraction, hence let
![]()
![]()
⇒ 1 = A(3u + 2) + B(2u + 1)……(ii)
We need to solve for A and B. One way to do this is to pick values for x which will cancel each variable.
Put
in the above equation, we get
![]()
![]()
![]()
Now put
in equation (ii), we get
![]()
![]()
![]()
We put the values of A and B values back into our partial fractions in equation (ii) and replace this as the integrand. We get
![]()
![]()
![]()
Split up the integral,
![]()
Let substitute
z = 2u + 1 ⇒ dz = 2du and y = 3u + 2⇒ dy = 3du so the above equation becomes,
![]()
On integrating we get
![]()
Substituting back the value of z, we get
![]()
Now substitute back the value of u, we get
![]()
Applying the rules of logarithm we get
![]()
Note: the absolute value signs account for the domain of the natural log function (x>0).
Hence,
![]()