C because the x's repeat with the 3 and 3. If the x's repeat it is not a function.
Hope that helps.
Answer:

Step-by-step explanation:
First, you have to substitute both functions into the equation to get:

Then, you distribute the negative sign in front of g(x) to get:

And finally, you add/subtract the x's that have the same power to get:

Where’s the window i think you forgot to attach something
Answer:
x = - 9, x = - 4
Step-by-step explanation:
Set (x +)(x + 9) equal to zero, that is
(x + 4)(x + 9) = 0
Equate each factor to zero and solve for x
x + 4 = 0 ⇒ x = - 4
x + 9 = 0 ⇒ x = - 9
Thus
x = - 9, x = - 4