Ana dives into a pool off of a springboard high dive. Her height (in meters above the water, x seconds after diving, is modeled by h(x)=-5(x+1)(x-3) How many seconds after diving will Ana hit the water?

She will hit the water after 3 seconds.

We first set the function equal to 0:
0=-5(x+1)(x-3)

Using the zero product property, we know that either x+1=0 or x-3=0.  Therefore our options are x=-1 or x=3.  Since x represents time, -1 makes no sense; therefore the answer is x=3.