Question 1

You have gone well to that point. Now what you need to do is substitute back to get the answer in terms of the variable of the question. IE .

So you have and and

Follow these substitutions you should get to right answer. Note that the final answer will have an term. There is nothing you can do about that.

Question 2

You answer looks right to me. The only thing you might want to do is collect the log terms together into

Question 3

Here you should use the substitution This gives

Then using partial fractions you can express the integrand as

You then should be able to integrate this easily and then don't forget to substitute back .

Hope this helps...