Factoring Question

Question

A smart-phone is thrown upwards from the top of a 192-foot building with an initial velocity of 16 feet per second. The height h of the smart-phone after t seconds is given by the quadratic equation . When will the smart-phone hit the ground?

Answer 1

It hits the ground when h=0. Set h(t)=0 and solve for t.

-16t² + 16t + 192 = 0

t² - t - 12 = 0

(t - 4)(t + 3) = 0

t must be positive, so the answer is 4 seconds.