A function is a certain rule that changes an input into an output.

For instance, the function 2x+3 multiplies an input by 2 and then adds 3.

By contrast, the function 2(x+3) adds 3 to an input and then multiplies by 2.

• We write functions like this:
  • f(x)=2x+3
  • g(x)=2(x+3)

In the above, the “x” is called the argument and represents the values that the function can take. So what do you think f(1) would be? What about g(1)?

Exercise

Let’s complete the short exercise 2C from pages 30 and 31 of the textbook:

The answers are below: