
a. Integrate by parts by taking


Then

We have

and so

or, replacing
,
.
b. From the above recursive relation, we find

Now,

and so we're left with
.
c. Using the previous result, we find
.
d. If the question is asking to find
, then you can just use the same approach as in (c).
But if you're supposed to find
, we have

Substitute

Then
