Question
Which table represents a linear function?
Table A
| x | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| y | 1/2 | 1 | 1 1/2 | 2 |
Table B
| x | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| y | 1 | 1/2 | 1/3 | 1/4 |
Table C
| x | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| y | 7 | 9 | 13 | 21 |
Table D
| x | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| y | 0 | 6 | 16 | 30 |
Answer
The first table represents a linear function.
| 1 | 2 | 3 | 4 | |
|---|---|---|---|---|
| 1 | 2 |
Each time increases by 1, increases by :
The rate of change is constant, so the points lie on one straight line. The equation is
Check the other tables
Second table
The outputs are . Their first differences are not constant. This table follows the reciprocal rule , which is nonlinear.
Third table
The outputs are . Their consecutive differences are , so the rate of change changes. The table is nonlinear.
Fourth table
The outputs are . Their consecutive differences are , so this table is also nonlinear.
Fast method
When the -values increase by equal amounts, subtract consecutive -values. A linear table must have the same first difference throughout. If the -increments are unequal, compare for every interval instead.
Evidence boundary
This answer matches the publicly visible Edgenuity Introduction to Linear Functions quiz item whose four tables use x-values 1, 2, 3, and 4 and the listed y-values. Edgenuity may randomize table order or values between course versions, so identify the constant rate rather than relying on an option position alone.
Sources
These references support the concepts and methods used in the explanation above.