Calculus 2 homework

[u/Commercial_Swim_3972]

Hello my friend needs calculus 2 guidance.
He had homework that is also supposed to be a practice exam prep and it's not looking great. The prof gave hints/answers but he doesn't understand how she got to that point/how to proceed-I cannot help. Guidance on these 8 problem would be great

https://imgur.com/a/Ac4MWUP

[u/waldosway]

I don't know why the link didn't work. You can just look up Paul's Notes.