Solve inequalities like equations, keeping the inequality sign. 3x + 4 < 19: subtract 4 to get 3x < 15, then divide by 3 to get x < 5.
One rule is different. If you multiply or divide both sides by a negative number, the inequality sign turns round. −2x > 6 gives x < −3. Check with a number: x = −4 makes −2x = 8, which is greater than 6. Show solutions on a number line with an open circle for < or > and a filled circle for ≤ or ≥.
Worked example
Solve 2x − 3 ≥ 9
- Add 3 to both sides: 2x ≥ 12.
- Divide both sides by 2.
Answer:x ≥ 6
Key words
- inequality sign
- <, >, ≤ or ≥
- reverse the sign
- turn it round when multiplying or dividing by a negative
- integer solutions
- the whole numbers that fit
Practise this
New questions every time.
Common Core-referenced: 7.EE.B.4b