If the Function Is One-To-One, Find Its Inverse $$f ( x ) = \frac { 9 } { x - 7 }$$

Multiple Choice

If the function is one-to-one, find its inverse. If not, write ʺnot one-to-one.ʺ
- $$f ( x ) = \frac { 9 } { x - 7 }$$

A) $f ^ { - 1 } ( x ) = \frac { - 7 + 9 x } { x }$
B) $f ^ { - 1 } ( x ) = \frac { x } { - 7 + 9 x }$
C) not a one-to-one
D) $f ^ { - 1 } ( x ) = \frac { 7 x + 9 } { x }$