Question

Write the inverse function for the function, ƒ(x) = 1/2x + 4. Then, find the value of ƒ -1(4). Type the answer exactly in this form.
ƒ -1(x) = ____a0 x ________a1 _______a2
ƒ -1(4) = ______a3

Answer 1

We can get the inverse function by first setting f(x) = y, solving for x, and after that switching y and x. So, let's solve for x:
$f(x)= \frac{1}{2}x+4$
$y= \frac{1}{2}x+4$
$2(y-4)=x$
$2x-4=y=f (x)^{-1}$

Then, just plug in 4 for x, and solve:
$2(4)-4= f (x)^{-1}$
$4=f (x)^{-1}$

There you have your answer.