Which Function Is It?
Tables
Example 2
Does the table below represent a linear or a quadratic function?
Step 1. Find the first difference.
Step 2. If the first difference is constant, the function is linear. If not, find the second difference.
Since the first difference is not constant, find the second difference.
Step 3. If the second difference is constant, the function is quadratic. If not, label the function as other.
This table has a common second difference, so it is quadratic.
The function that models this table is 
.