1 correct
2 incorrect
3 not sure what your final answer is here but you don't have it correct
4 incorrect
You can always take the derivative of your solutions as a check too.
These problems are part of my homework. However, I am bit unsure about some of them, so I'd like to ask you whether my answers are correct. If you find mistakes and have the time please write me the full solution. Thx
Pr.1 Let
Pr.2
Let
Pr.3 Then
Pr.4 Let