To determine

To find: The formula for the inverse of the function.

Answer

Answer: f-1x=x-12-23

Explanation

fx=1+2+3x

Step 1: Substitute y=1+2+3x .

Solve the above equation for x: y-12=2+3x  ⇒ x=y-12-2/3.

Step 2: Interchange the positions of x and y, we get y=x-12-23.

Conclusion: Thus,f-1x=x-12-23.