Inequalities
Statements using <, >, or the signs for 'less than or equal' and 'more than or equal' that show a range of possible values.
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Analogy
Like a height rule on a fairground ride: anyone at least 1.2 m can ride, so there are many valid heights.
Example
2x < 8x < 4So x can be 3, 2, 1, 0, ...
In practice
A lift sign saying 'maximum 8 people' means the number of people must be 8 or fewer.
Practice
Flashcards
- Solve 2x + 3 < 11.x < 4.
- When do you flip an inequality sign?When you multiply or divide both sides by a negative number.
Questions people ask
When do you flip the inequality sign?
Flip the sign when you multiply or divide both sides by a negative number. For -2x < 8, dividing by -2 gives x > -4, not x < -4. In all other steps, the sign stays the same. Test it: x = 0 gives 0 < 8, which is true.
How do you show an inequality on a number line?
Draw an open circle for < or >, because the end number is not included. Draw a filled circle for the 'or equal to' signs. Then shade the line in the direction of the allowed values. For x < 4, shade left from an open circle at 4.