Inverses

Finding the Inverse

To find an inverse symbolically:

1. Substitute y for f(x).

2. Interchange the x and y variables - this is the foundation behind inverses.

3. Solve the new equation for y.

4. Substitute f-1(x) for y.

Example 1 Find the inverse of the function f(x) = 5x -2.

Step 1. Write the original function using y notation.

y = 5x -2

Step 2. Interchange x and y.

x = 5y - 2

Step 3. Solve the new equation for y.

Find ex1

Step 4. Simplify if possible and change to inverse function notation.

Find_Ex1-2