Question

A softball is thrown from the top of a 30ft building. The height of the ball is modeled by

h(t) = -16ť? + 20+ + 30
where t is time in seconds.
How long does it take for the ball to hit the ground?
Question to answer: How long does it take for the ball to hit the ground? Round to the nearest tenth.
The ball hits the ground at
seconds.

Answer 1

2 seconds

Explanation:

When the ball hits the ground, its height (h) will be 0. You can therefore set up the following equation:

`0=-16t^2+20t+30 \\\\-4(4t^2-5t-6)=0`

Factor:

`-4(4t+3)(t-2)=0 \\\\t=-(3)/(4), 2`

Since the time must be positive, it hits the ground after 2 seconds. Hope this helps!