3. Find the second derivative of a function f(x) , if the first derivative is f'(x) =-7x3 cos(12x?). (3 marks) 4. The equation of the elastic curve (deflection) for a simply supported beam under uniform load is given by y = 2x10- x (120-7 x2 + x), in which, x is the distance from the left support of the beam to any point on the beam, and y is the deflection, both in meters. Find the rate of change of the deflection of the elastic curve at x = 2 m. (4 marks)