Hi differentiate

This step is wrong. You have to state z^2 in term of u before integrating it.

This step is wrong. You have to state y in term of u before integrating it.QUESTION TWO

This step is wrong. You have to state x in term of u before integrating it.QUESTION THREE

What is your u ? ( I suppose it's 2x-1). And you have the same mistake as previous questions.QUESTION FOUR

If incorrect, please enlighten me with regards to the correct way to do these. sorry, I'm really bad at Maths

Thank you.