Question

a ball is thrown from an initial height of 5 feet with an initial upward velocity of 21ft/s . The ball's height h (in feet) after seconds t is given by the following.
h=5+21t-16t^2

Find all values of t for which the ball's height is 11 feet.
Round your answer(s) to the nearest hundredth.
(If there is more than one answer, use the "or" button.)

Answer 1

i got t=.42,.89