I don't really get this method, it wasn't explained thoroughly in the book. It says:

"Differentiate term by term through the function, remembering that in differentiating functions of y you are differentiating a function of a function".

Then it gives an example:

Find of

I don't know why . I know that y is really a polynomial in x and that 'somehow' complicates things, but it doesn't make sense to me to just add a to the end

I also never knew you could differentiate an 'equation'... could you effectively write this Equation ?