The height h (in feet) of a volleyball t seconds after it is hit can be modeled by h=16t2+48t+4. How long is the volleyball in the air?

1 Answer
Nov 15, 2015

t=3.08s

Explanation:

We have to substitute h by 0, as that is the height both when projected as when it hits the ground. Then we solve for t:
16t2+48t+4=0,
16t248t4=0,
4(4t212t1)=0,
4t212t1=0. Now we use t=b±(b24ac)2a:
t=(12)±(12)24(4)(1)2(4),
t=12±144+168,
t=12±1608,
t=3.08s.

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