Try again. If the first three steps have produced no answer, try harder.
Try substitution. You may not have tried all the possibilities for the given integral.
Integration by parts. Even if your integral does not have the form described in (3c), integration by parts may still work. Remember that it works sometimes on single functions. We used it to find ∫▒〖sin^(-1) xdx,∫▒〖tan^(-1) xdx〗〗 and ∫▒In xdx
Manipulate the integrand. Try to change the integrand using algebraic manipulations, rationalizing. If the integrand involve trigonometric functions, try to rewrite it in terms of other trigonometric functions using identities.
Relate the problem to other problems. Think if you have done a similar problem in the part and how you did it. This is why it is important to remember the problems you do and analyze them.
Use several methods. Sometimes, several methods may be used. Either you will repeat the same method several times, or you will mix the various methods studied.
We give a few examples to illustrate these guidelines. In each example, we indicate the method to use but do not carry out the integration.