Question

A ball is thrown from an initial height of 7 feet with an initial upward velocity of 17ft/s . The ball's height h (in feet) after seconds t is given by the following. h=7+17t-16t^2 Find all values of t for which the ball's height is 11 feet. Round your answer(s) to the nearest hundredth.

Answer 1

Hello,

-16t²+17t+7=11
==>16t²-17t+4=0
Δ=17²-4*4*16=33
==>t= (17-√33)/32=0.351732... (s)≈0.35 (s)
or t=(17+√33)/32=0.710767 (s)≈0.71 (s)