Year 9 Interactive Maths - Second Edition

Dividing Each Side of an Inequality by a Positive Number

If you put 10 kilograms in one of a pair scales and add 6 kilograms to the other, the scales will show that 10 kg is heavier than 6 kg.  That is, 10 > 6

Divide each side by 2

In general:

Both sides of an inequality can be divided by the same positive number.

Example 25

Solve the inequality 10x > 40 for x.

Solution:

Note:

(i)  The solution set consists of all numbers greater than 4, and is shown on the number line as follows:

      The ring at 4 in this diagram means that 4 is not an element of the solution set.