If [tex]f^{-1}(x)[/tex] is the inverse of f(x), then
[tex]f\left(f^{-1}(x)\right) = x[/tex]
By definition of f(x), we have
[tex]f\left(f^{-1}(x)right) = 6f^{-1}(x) + 4 = x[/tex]
Solve for the inverse :
[tex]6f^{-1}(x) + 4 = x[/tex]
[tex]6f^{-1}(x) = x - 4[/tex]
[tex]f^{-1}(x) = \dfrac{x-4}6[/tex]
which makes C the correct choice.
