A football is punted. Its height, H metres is given by the quadratic relation with equation: H = -5t^2 + 21t, where t is the time in seconds after the punt.
Algebraically determine the maximum height of the football. Show all of your steps.
again, you want the vertex.
-5t^2 + 21t
= -5(t^2 - 21/5 t + (21/10)^2) + 5(21/10)^2
= -5(t - 21/10)^2 + 441/20
so the max height is 441/20 meters
or, we know the vertex is midway between the roots of 0 and 21/5
so find h(21/10) = 441/20