Question

A football is kicked from ground level at an initial upward velocity of 90 feet per second. The equation h=−16t2+90t
gives the height h of the football after t seconds.

Using the equation, what is the domain when the maximum range is achieved? Round to the nearest tenth.

(1 point)

2.8 feet

2.8 seconds

126.6 feet

126.6 seconds

Answer 1

2.8 seconds.

The vertex time is t = −b/(2a) = −90/(2·−16) = 90/32 = 2.8125 ≈ 2.8 s, so the maximum height occurs at about 2.8 seconds.