Question

Anthony throws a ball from a point of 40m above the ground. The height of the ball h, in meters, after t seconds is represented by the function h(t) = -5t2 + 40t.

What was the maximum height
of the football?
How many seconds did it take
for the football to hit the ground?

Answer 1

maximum height is 80 feet

8 seconds until it hits ground

Explanation:

-5t(t - 8) = 0

-5t= 0; t = 0 (this represents the beginning of the throw)

t-8=0; t = 8 (this represents the end of the throw)

To find maximum height, find the vertex of the graph,

you can use -b/2a to find 't' and then substitute that value back into the function to find h(t)

x = -40÷2(-5)

x = -40/-10

x = 4

h(4) = -5(4²)+40(4)

h(4) = -5(16) + 160 which is 160 - 80 = 80