e
step-by-step explanation:
an equation by definition has to have two or more variables (x and 2 in this case)
is their an equation anywhere i can take a look at it and see if i am right.
f(x) is are being squared
g(x) is increasing by 2
h(x) is adding .25 each time
k(x) is taking the square root
f(x) and k(x) are exponential functions