h(t) is the height of the diver in feet above the water
Now it asks about the time at which diver reaches the water
When diver reaches the water , the height of diver from water should be zero
So we plug h(t) =0
So

divide whole equation by -16

we can now factor the quadratic equation
So we get
(t+4)(t-3) =0
plug each factor equal to zero and solve for t
t+4 =0 and t-3 =0
So t=-4 and t=3
Now time cannot be negative , So t=3
So time = 3 seconds
It takes 3 seconds for the diver to reach the water
We have been given the expression

We have to write this expression in the form 
In order to write the given expression in this form, we can use some exponent property.

On using the property (1), we have

Now, on using the property (2), we get

Therefore, the simplified form of the given expression is
