Hi I just finished some questions and got these wrong, I won't get to ask anyone till a few days late, so I would really appreciate your help!

1.) Differentiate

Using quotient rule, I got

Simplifying,

, why is this wrong?

2.) Differentiate

I got , why is this wrong?

3.) If a, b and c are functions such that a(x) are not 0 for all x and c(x) = a(x)b(x) then c'(d)=0 for d is all real numbers such that a'(d)=0 or b'(d) =0.

I wrote that it's true becuase I thought the last part of the question made sense..but it's false, why is it so?

4.) Suppose a,b and c are functions such that a(x) is not 0 for all x and c(x) = b(a(x)) then c'(d)=0 for d is all real numbers such that a'(d)=0.

I wasn't sure so I thought it was false..

Thank you!