Which Function Is It?
Tables
The table of a linear function will have a common first difference, while the table of a quadratic will have a common second difference.
Example 1 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.
The first difference is constant, so the function is linear.
The equation of the function is y = 2x + 9.