Remember that a function is a set of arithmetic operations being applied to an input to make an output. So the function f(x)=2x-4 multiplies an input by 2 and then subtracts 4.

There are two ways that we can find the **inverse of a function**. One is by working backwards from the last operation and inverting each of the operations. We will demonstrate this in the below example:

**Example**

Another, generally quicker, method is to follow a special algorithm. We switch the variables of the equation and then make the other variable into the subject of the equation. We will demonstrate this below in “example 12”

**Exercise**

Let’s complete exercise 14J on pages 233 and 234 of the textbook:

The answers are below: (N.B. 6c answer is wrong – what should it be?)