Answer:
b. 4.5 seconds
Step-by-step explanation:
We must calculte the zeros of the function f.
[tex]f(x)=-16x^2+72x[/tex]
[tex]-16x^2+72x=0[/tex] distribute
[tex]-8x(2x-9)=0\iff-8x=0\ \vee2x-9=0[/tex]
[tex]-8x=0[/tex] divide both sides by (-8)
[tex]x=0[/tex]
[tex]2x-9=0[/tex] add 9 to both sides
[tex]2x=9[/tex] divide both sides by 2
[tex]x=4.5[/tex]
The ball in the air was from 0s to 4.5 seconds. That's why your answer is 4.5 seconds.
