Question

PLEASE HELPPP!!!! WILL GIVE BRAINLIEST!!!

Answer 1

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