The derivative of is: .
Remember you want to use the definition of a derivative but leave the functions in terms of , so you want to solve the difference quotient:
It may help to not actually simplify much for and terms individually, as there will be a lot of cancellation between them, so you may
want to write it out long-way and see how much canceling you can do term-wise before you try to simplify! Remember, when in doubt,
expand everything as much as you can and combine like terms, or if you have a radical, you may need to rationalize the numerator.