Hey everyone, first post ever in here. This is my 2nd time taking Calculus 2 and I feel like I am worse off than the first time.

I have a quick set of 4 problems that Im not sure I understand how to do. Apparently 1, 2 and 3 can be solved with u-substitution and a formula, while 4 just needs a u-substitution.

Here are the problems, sorry about the format:

1:

2:

3:

4:

I feel like Ive lost a lot of my fundemental calc skills.

Thanks in advance!!

-WhiteX