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

[mathdad]

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?

 

[Euge]

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

Yes.

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

Yes.

 

[mathdad]

Good to know that I am right.