If f(x) = 3x 7, what is f(-2)? a. -2 b. 13 c. 1 d. -1

The given function is ⇒⇒⇒  y = x² + 4x + 4

To find the inverse of the function, we need to make x as a function of y and at the final step make a switch between x and y (i.e. make x as y and y as x)
y = x² + 4x + 4  ⇒⇒⇒ factor the quadratic equation
y = (x+2)(x+2)
y = (x+2)²         ⇒⇒⇒ take the square root to both sides
√y = x+2
x = √y - 2         ⇒⇒⇒ x becomes a function of y
final step:
∴ y = √x - 2   ⇒⇒⇒ the inverse of the given function

So, as a conclusion:
f(x) = y = x² + 4x + 4  ⇒⇒⇒ the given function

f⁻¹(x) = y = √x - 2       ⇒⇒⇒ the inverse of the given function