Right now that equation is a function of time, h(t), height with respect to time. If the baseball is on the ground, it has no height. In other words, its height = 0. So if we set the equation equal to 0 and solve for t, time, that will tell us the time that the ball had a height of 0. If you plug those numbers into the quadratic formula, which is the best and most efficient way to factor a quadratic, you will get that the times are -.0615528128 and 4.061552813 seconds. The 2 things in math that will never EVER be negative are time and distance/length. So we know that the ball will not hit the ground at -.062 seconds. Therefore, it hits the ground 4.06 seconds after it was hit.
see how it do it in the picture and hope it helps you..
Angles that combine to make a straight line add up to __180__ degrees.
I hope this helps! :)