Identifying Functions

8th Grade15 minutes

Learning Objective

I can identify functions from graphs, tables, and other representations.

Key Concepts

In a function, each input (x-value) should produce only one output (y-value), like a vending machine that dispenses the same item each time you press the same button.

If a vertical line drawn on a graph intersects the graph at more than one point, then the graph does not represent a function.

To keep a table a function, if an x-value repeats, it must have the same y-value.

Practice Questions

This lesson includes 3 practice questions to reinforce learning.

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1. Which of the following tables represents a function?

2. Explain how the vertical line test can be used to determine if a graph represents a function.

3. Consider the set of points: (1, 5), (2, 6), (3, 7), (4, 8). Which of the following points could be added to this set so that it remains a function?

Educational Video

GED Math – Determine Functions!

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