Find the vertex:

Determine if the parabola will open up or down:

Since the value of a is positive, the parabola will open upwards
Find the x and y intercepts:
Factor
to find the x intercepts
(x+8)(x+2)
x + 8 = 0
x = -8
x + 2 = 0
x = -2
x intercepts:
x = -2
x = -8
Find the y intercept

Hence, C. Graph A best represents the quadratic function 
Answer:
-3
Step-by-step explanation:
-15 divided by 5= -3
Answer:

Step-by-step explanation:
The x-axis represents
and
is 3. The y-axis represents
and
is -4 so
is -4i.