A ball is launched into the sky at 19.6 feet per second from a 58.8 meter tall building. The equation for the ball's height. h, at time t seconds is h=-4.9t^2+19.6t+58.8. When will the ball strike the ground

H represents the height of the ball at a given time, symbolised as t.

Thus, we just need to find when h = 0 so that we find when it hits the ground.

0 = - 4.9t² + 19.6t + 58.8

0 = 4.9t² - 19.6t - 58.8

0 = 49t² - 196t - 588

0 = t² - 4t - 12

0 = (t - 6) (t + 2)

So, t = 6 or - 2, but t ≠ - 2, since time cannot be negative in this instance.

Hence, at 6 seconds, the ball will strike the ground.