Answer:
[tex]f^{-1}(x) = 9x -18.[/tex]
Step-by-step explanation:
[tex]y=f(x)=\dfrac 19 x +2\\\\\text{Replace x with y and then solve for y,}\\\\~~~~~~~x = \dfrac 19 y+2\\\\\implies 9x =y + 18~~~~~~~~~~~~~~~;[\text{Multiply both sides by 9}]\\ \\\implies y = 9x -18\\\\\implies f^{-1}(x) = 9x -18\\\\\text{Hence, the inverse of the given function is}~ f^{-1}(x) = 9x -18.[/tex]
