Algebra
posted by TJ .
How would I work this?
The equation h= 16t^2 +112t gives the height of an arrow shot upward from the ground with an initial velocity of 112 ft/s, where t is the time after the arrow leaves the ground. Find the time it takes for the arrow to reach a height of 120 ft.

set your h equal to 120 and solve that routine quadratic equation.
You will get two answers for t, one will be the time to reach 120 feet on its way up, and the other the time when it was 120 feet high on its way down.