Question 301613
The height of a ball in feet is modeled as f(x)=-16x^2+96x, where x is the time in seconds after it is hit. How long is the ball in the air?
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The time it is in the air is equivalent to the time it hits the ground -- so, set f(x) to 0 and solve for t:
f(x)=-16x^2+96x
0=-16x^2+96x
0=16x^2-96x
0=x^2-6x
0=x(x-6)
x = {0,6}
Solution: 6 seconds