C = $7s
independent variable ie the changing variable is s
dependent variable ie the non changing variable is c
Part A
We have

. To solve for the x-intercept, we set f(x) equal to 0. That is

Take the square root of both sides,
The x-intercept is (-2,0).
To solve for the y-intercept, we set x=0. That is
The y-intercept is (0, 8)
The coordinates of the optimum point are actually the vertex which can be easily seen from the vertex form equation given above. The minimum point is
(-3, -1).
Part B.
We have

.
Factor out -2

Complete the square

Simplify

Part C
We have

.
The maximum height is 12.25 feet after 0.875 seconds from the time of the jump. The dolphin will be back in the water after 1.75 seconds. The graph of the jump is shown in the photo.
8x + y - z
You can tell because each term is separated by an operator such as +, -, *, or /