Answer:
B. 3/2
Step-by-step explanation:
If f(x) and [tex]f^{-1}(x)[/tex] are inverse, that means that if we switch the x and y for f(x) and solve for y, we will get the inverse function.
Knowing that f(x) = 2x + 5, let's write this as y = 2x + 5 and switch the x and y:
x = 2y + 5
Now, solve for y:
x = 2y + 5
x - 5 = 2y
y = (x - 5)/2
That's the [tex]f^{-1}(x)[/tex] function: [tex]f^{-1}(x)=\frac{x-5}{2}[/tex]
Plug in 8 for x:
[tex]f^{-1}(x)=\frac{x-5}{2}[/tex]
[tex]f^{-1}(8)=\frac{8-5}{2}=3/2[/tex]
The answer is thus B.
~ an aesthetics lover
