Here we will show an alternative way to get from a general partial fraction with a quadratic factor to simpler forms.
The starting point is again the idea that we can use x in the
numerator to set up a quadratic substitution, but this time we do not delay
it for after getting rid fo the linear part. But if we want to do such a
substitution right away, then we need to create the expression
We get
Now we can easily integrate the first integral using the obvious quadratic substitution.
The second integral in decomposition above had only a constant in its numerator, se it is possible to transform it using completion of square into an integral leading to asc tangent, just like in the recommended algorithm.