MHB Yes, you are correct for both parts (A) and (B)!

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The height of a ball thrown upward is modeled by the equation h = -16t^2 + 96t. To determine how long it takes for the ball to drop, set h to 0 and solve for t. For the height to be 80 feet, set h to 80 and solve for t, which yields two solutions due to the ball's upward and downward paths. This dual solution occurs because the ball reaches 80 feet on its way up and again on its way down. The discussion confirms the correct approach for solving both parts of the problem.
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A ball is thrown straight upward. Suppose that the height of the ball at time t is h = -16t^2 + 96t, where h is in feet and t is in seconds, with t = 0 corresponding to the instant that the ball is first tossed.

(A) How long does it take for the ball to drop?

(B) At what time is the height 80 feet? Question (B) has two answers. Why?

To answer part (A), do I set h = 0 and solve for t?

To answer part (B), do I set h = 80 and solve for t?
 
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RTCNTC said:
To answer part (A), do I set h = 0 and solve for t?

Yes.

RTCNTC said:
To answer part (B), do I set h = 80 and solve for t?

Yes.
 
Good to know that I am right.
 
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