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For inequalities on a number line, what does it mean when a point is open or closed?
We want to find the graph of the given inequality. To graph an inequality on a number line, we need to make note of two things. The first thing is the direction of the inequality and the second thing is whether it is strict. Let's consider the given inequality.
| Symbol | Strict / Non-strict | Example | Meaning |
|---|---|---|---|
| < | Strict | x<1 | The variable x is less than 1. |
| ≤ | Non-strict | x+1 ≤ -3 | The algebraic expression x+1 is less than or equal to - 3. |
| > | Strict | 2x-5 > 5 | The expression 2x-5 is greater than 5. |
| ≥ | Non-strict | x ≥ 2x+1 | The variable x is greater than or equal to the expression 2x+1. |
With an inequality, it is possible to compare any combination of two numbers, variables, numeric expressions, or algebraic expressions. As can be seen in the table, there are four different types of inequalities. There are several ways each inequality can be phrased.
| Symbol | Key Phrases |
|---|---|
| < | & ∙ is less than & ∙ is fewer than |
| > | & ∙ is greater than & ∙ is more than |
| ≤ | & ∙ is less than or equal to & ∙ is at most & ∙ is no more than |
| ≥ | & ∙ is greater than or equal to & ∙ is at least & ∙ is no less than |