Any idea ?

4. Integration by Parts can also be used to generate reduction formulas. These formulas express the value of an integral (where a function is raised to an integer power n) in terms of a similar integral for a smaller power of n. These patterns can be applied repeatedly until the power is broken down into something that can be easily integrated, allowing one to get the answer fairly quickly. One such formula is a reduction formula for cosine: cos" (x)da = = cos" '(r) sin(:) + 1 cos" (x)de. TL Use this formula to evaluate / cos(x)do. 5. What two conditions must a and b satisfy so that the u-substitution method will be successful in evaluating the following integral? at + b (12 - c + 5)2 (Note: The answer is not just a = 2, b = -1. What can you say about the relationships between a and b?)