8. Amy throws a ball so that when it is at its highest point, it passes through the centre of a
hoop. The path of the ball is modelled by the equation y=h+kx-x², where y is the
height in metres of the ball above the ground and x is the horizontal distance in metres
from the point at which the ball was thrown. The centre of the hoop is at the point where
x=2 and y = 5.
(a) Find the values of h and k.
(b) Find the value of x at which the ball hits the ground.