yeah, second part should be fine once the first part is proved but first part i just cant get
There isn't much to this question other than following through with the algebra and not making silly mistakes. Maybe post your working? It might just be a silly mistake you made.
They are just a telescoping sum and product respectively. Like, write out the first few terms and you'll see most of the stuff will cancel. If you guess a formula using a calculator, you should prove it by induction or something in order to show working out.
For questions 14b and 15d, what is the actual working out? Are you just supposed to tell what they are by trial and error using a calculator?
Just expand the factorisation and then differentiate as normal. So for a) the expansion is x^3 + x, and if you differentiate that you get 3x^2 + 1
The gradient for that question is where the dy/dx value is equal to -2. (it is the slope)
