Example

Example: Demonstrating the Multiplication and Division Properties of Inequality with a Negative Number

Consider the true mathematical statement 10<1510 < 15. If we multiply both sides by the negative number −5-5, we get 10(−5)10(-5) and 15(−5)15(-5), which evaluate respectively to −50-50 and −75-75. Because −50-50 is greater than −75-75, the inequality symbol must reverse its direction, resulting in the true mathematical statement −50>−75-50 > -75. Similarly, dividing both sides by −5-5 yields 10−5\frac{10}{-5} and 15−5\frac{15}{-5}, which evaluate to −2-2 and −3-3. Because −2-2 is greater than −3-3, the symbol again reverses to give −2>−3-2 > -3. These numerical examples verify that multiplying or dividing an inequality by a negative number requires reversing the inequality sign to properly maintain a true mathematical statement.

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Updated 2026-06-03

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