Question

Someone please help me

Answer 1

b. 4.5 seconds

Explanation:

We must calculte the zeros of the function f.

`f(x)=-16x^2+72x`

`-16x^2+72x=0` distribute

`-8x(2x-9)=0\iff-8x=0\ \vee2x-9=0`

`-8x=0` divide both sides by (-8)

`x=0`

`2x-9=0` add 9 to both sides

`2x=9` divide both sides by 2

`x=4.5`

The ball in the air was from 0s to 4.5 seconds. That's why your answer is 4.5 seconds.