Question

How do I know if the function is a linear function?

Answer 1

This is not a linear function.

Explanation:

It is a quadratic function. If you were to make a table of the x and y values of the function it would look like this:

x y

0 -4

1 -1

2 8

Just by looking at these three values, we can see that they do not increase at a consistent rate. It increases by 3 from 0 to 1, but increase by 9 from 1 to 2. You can tell if a function is linear by seeing if it increases at a constant rate. (In this case it does not)