I would really appreciate if anyone could sold question 201 please.

We need to find f inverse.
f(x) = 2(x - 4)^2
Let y = f(x)
y = 2(x - 4)^2
x = 2(y - 4)^2
x/2 = (y - 4)^2
sqrt{x/2} = sqrt{(y - 4)^2}
sqrt{x/2} = y - 4
sqrt{x/2} + 4 = y
y = sqrt{x/2} + 4
Let y = f^(-1) x
f^(-1) x = sqrt{x/2} + 4