Rule

Multiplying and Dividing Inequalities with a Negative

There is one important difference between solving equations and solving inequalities. When dividing or multiplying the inequality by a negative number, the inequality symbol must be reversed or flipped.

Consider the following example to understand why the inequality symbol is reversed. The inequality
is a true statement. Multiplying both sides by results in
Notice that is smaller than Thus, the inequality symbol that makes this a true statement is Therefore, when multiplying or dividing an inequality by a negative number, the inequality symbol must be reversed.
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