SOLUTION: 1. A ball is hit upward. Its height h in feet after t seconds is given by h=-16t^2 + 80t + 4. At what times is the ball 100 feet in the air? searcheagle@yahoo.com

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: 1. A ball is hit upward. Its height h in feet after t seconds is given by h=-16t^2 + 80t + 4. At what times is the ball 100 feet in the air? searcheagle@yahoo.com      Log On

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Question 441499: 1. A ball is hit upward. Its height h in feet after t seconds is given by
h=-16t^2 + 80t + 4. At what times is the ball 100 feet in the air?
searcheagle@yahoo.com
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


You have a projectile launched vertically at 80 feet per second initial velocity from a position 4 feet above ground level (height zero).



gives the height at seconds if the instant of launch is

You want to know the value of when

So:





Just solve the quadratic for the two values of . Hint: Divide through by -16 and then factor the resulting trinomial.

John

My calculator said it, I believe it, that settles it
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