PLS HELP IM GIVING AWAY 50 POINTS

A diver jumps from a diving board that is 24 feet above the water.
The height of the diver is given by:
h=-16(t-1.5)(t+1)
Where the height h is measured in feet, and the time t is measured in seconds. When will the diver hit the water? Can you see a quick way to find the answer? EXPLAIN