If the Function $f ( x ) = 9 x - 4$

Multiple Choice

If the function $f ( x ) = 9 x - 4$ is one-to-one, find its inverse.

A) $f ^ { - 1 } ( x ) = \frac { x - 4 } { 9 }$
B) $f ^ { - 1 } ( x ) = \frac { 1 } { 9 x - 4 }$
C) $f ^ { - 1 } ( x ) = \frac { x + 4 } { 9 }$
D) not one-to-one