Will give ! h(t)=−16t^2+28t the function h(t) gives the approximate height, in feet, of a dolphin's jump out of water, where t represents the time, in seconds. what is the total length of time, in seconds, it took the dolphin to complete one jump? show your work.

We find the zeros of h(t), which is where the height is 0. When the height is zero, the dolphin will be in the water.
Set h(t) = 0
0=-16t^2+28t
Factor out -4t:
0= -4t(4t - 7)
The zeros, by zero factor property we set every factor to zero and combine solutions

t = 0 .. or ... 4t - 7 = 0
t = 0 .. or ... 4t = 7
t = 0 .. or ...   t = 7/4
t = 0 .. or ...   t = 1.75

since h(t)=−16t^2+28t is a parabola that opens down the dolphin gets out of the water at t = 0 and then gets back in at t = 1.75 (the vertex of their height is in between).

The total length is 1.75 seconds