Inverse

Problem:



Solution:

It is easy to find the inverse first

Let $ y = 5x - 3 $, we solve for $ x $ give $ x = \frac{y + 3}{5} $, that is the inverse.

The rest is just value substitution exercise.

a) $ f^{-1}(8) = \frac{8 + 3}{5} = \frac{11}{5} $
b) $ f^{-1}(y) = 17 $ implies $ y = f(17) = 5 \times 17 - 3 = 82 $.
c) This is trivial, $ b = 1 $.
d) And so is this, the answer is 103.