Question 4 (9 marks) For the following functions: (i) Differentiate them using first principles. ((a) =3 marks, (b) = 4 marks) (ii) Determine the gradient of the tangent to the curve at the point where x = 3. ((a) = 1 marks, (b) = 1 marks) (a) y = x(x+3) (b) f(x) = 5 (x-1)2 Question 5 (15 marks) a) By considering the gradient of the secant through the points P(x, f (x)) and Q (x + h, f(x + h)) on the curve f(x) = x3 - 6x + 1, find the derivative f'(x). (3 marks) (Hint: It's asking you to find f' (x) using first principles)