Solving Inequalities by Multiplication or Division

Solving Inequalities by Multiplication or Division

Secondary 3

Properties

Examples

If \(x\ge y\)and \(d>0\)(positive number) , then   \(dx\ge dy\) and \(\frac{x}{d}\ge \frac{y}{d}\) (sign is not reversed)

If \(x\le y\) and \(d>0\)(positive number) , then

\(dx\le dy\) and \(\frac{x}{d}\le \frac{y}{d}\) (sign is not reversed)

If \(x\ge y\) and \(d<0\), then \(dx\le dy\) and \(x/d\le y/d\).

If \(x\le y\) and \(d<0\), then \(dx\ge dy\) and \(x/d\ge y/d\).

Inequality sign does not change when we multiply or divide by a positive number on both sides of inequality but

Inequality sign changes when when we multiply or divide by a negative number on both sides of inequality.

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