Directed numbers are inequalities that describe a set of numbers. The inequalities may be represented on a number line.
The diagram below represents the inequality
The filled in black circle at
indicates that 2 satisfies the inequality.
The diagram below represents the inequality
The white filled in circle at
indicates thatdoes not satisfy the inequality.
The above examples illustrate an important convention. If an inequality is written down and the value of x in the inequality is included,
or
signs are used.
We can also write down inequalities that indicate that numbers greater than (or equal to) some number and less than (or equal to some other number) are required.
The diagram below indicates that numbers greater than -2 but less than 4, written
are required:
The diagram below indicates that numbers greater than or equal to -2, written
but less than 4 are required:
The diagram below indicates that numbers greater than or equal to -2 and less than or equal to 4, written
are required:
