SOLUTION: Why is any linear inequality not a function?

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Question 1014943: Why is any linear inequality not a function?
Found 2 solutions by Fombitz, robertb:
Answer by Fombitz(32388) (Show Source):
You can put this solution on YOUR website!
A function requires a unique y value for each x value.
An inequality allows for multiple solutions, so you have multiple y values for a given x value so it's not a function.
Example:

So for , is a solution and so is etc. so it's not a unique y for each x value so it's not a function.

Answer by robertb(5830) (Show Source):
You can put this solution on YOUR website!
Graphically speaking, the solution set of a linear inequality is a region in . This means any vertical line will cross the solution set in at least two points, violating the vertical line test, an essential criterion for functionality.