M4.8.3 For the adult
Inequalities
The answer to 3x − 4 < 11 is not one number. How do I show every answer?
What this chapter teaches
An inequality has many answers, shown on a number line. An open circle leaves the end out and a filled circle keeps it. Solve it like an equation, but flip the sign when you multiply or divide both sides by a negative number.
Three questions to ask
There is no one right wording. Listen for the idea.
- What is the difference between x > 3 and x ≥ 3, and how does the number line show it?
- Why does −2x < −6 become x > 3 and not x < 3?
- Which whole numbers fit −2 < x ≤ 3, and why is −2 not one of them?
After the chapter, the learner can
- Solve 3x − 4 < 11 and show it on a number line
- Solve an inequality where you must flip the sign
- List the whole numbers that fit −2 < x ≤ 3
What they copy into their notebook
Open circle: not included. Filled circle: included. Solve like an equation. Flip the sign only when you multiply or divide by a negative number.