Math  solving quadratic equations with factoring
posted by Amy on .
A person jumps off a 20m high cliff into water below. The height of the person above the ground at time t seconds is given by the equation h=5t^2+30. How long does it take the person to reach the half way mark to the water?

10 = 5t^2 + 30
5t^2 = 20
t^2 = 4
t = 2