Given function is f(x) = 9x or y = 9x.
First step is to find the inverse is switch x and y. Therefore, the above equation will be:
x = 9y.
Next step is to solve the equation for y to get the inverse of f(x). So, divide each sides by 9 to isolate y. Hence,
[tex] \frac{x}{9} =\frac{9y}{9} [/tex]
y = [tex] \frac{x}{9} [/tex]
So, the correct choice is A: [tex] f^-1(x)=\frac{x}{9} [/tex]
