Define the function \(f(x) = 2x - 5\). For what value of x is f(x) equal to \(f^{-1}(x)\)?
For the function: f(x) = 2x -5:
First, find the inverse:
step 1) replace "f(x)" with "y": y = 2x -5
step 2) interchange x and y: x = 2y - 5
step 3) solve this equation for y : x = 2y - 5
x + 5 = 2y
(x + 5)/2 = y
y = (x + 5) / 2
step 4) replace "y" with "f-1(x)": f-1(x) = (x + 5)/2
This equation is the inverse.
Now, solve the problem: For what value of x will f(x) = f-1(x)?
Set f(x) = f-1(x) ---> 2x - 5 = (x + 5)/2
4x - 10 = x + 5
3x - 10 = 5
3x = 15
x = 5