4: You get
The first fraction is integrated by substitution. In the second you first get
rid of the nine in the denominator, either by factoring out or by the
substitution
If you remember the reduction formula, use it and the problem is solved. If
not, perhaps you remember how the reduction formula was deduced and repeat
the process for this particular case. If you have no memory regarding the
reduction business, skip it and try a different approach: You face an
integral with a power of a
quadratics, for which there is a standard method - in this particular
case it is the tangent substitution. Here you can even connect this
substitution with the simplifying process, namely, you would use the
substitution