Question

What is the inverse of the function f(x) = 4x + 8?

h(x) = x – 2
h(x) = x + 2
h(x) = x – 2
h(x) = x + 2

Answer 1

replace f(x) with y
swtich x and y
solve for y
replace y with f⁻¹(x)

f(x)=4x+8
y=4x+8
x=4y+8
x-8=4y
1/4x-2=y
y=1/4x-2
f⁻¹(x)=1/4x-2
none of the above

Answer 2

we have

$f(x)=4x+8$

Step 1

Let

$y=f(x)$

$y=4x+8$

Step 2

exchanges the variable x for y and the variable y for x

$x=4y+8$

Step 3

Isolate the variable y

$4y=x-8$

$y=\frac{1}{4}x-2$

Step 4

Let

$h^{-1}(x)=y$

$h^{-1}(x)=\frac{1}{4}x-2$ ------> the inverse function

therefore

the answer is

$h^{-1}(x)=\frac{1}{4}x-2$