The equation ​ describes the height (in feet) of a projectile launched from the ground at 80 feet per second. At what will the

  36    =  -16t^2 + 80 t

-16t^2 +80t -36 = 0        use quadratic formula to find values of  t

a = -16    b = 80   c = -36

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)                         the smaller 't' value will be the FIRST time it is at 36 ft 

                                                               the other 't' value will be when it is on the way down

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