Year 8 Factorising Expressions (Common Factors) Worksheet — Level 2 — Practice Set 3 — Answers
Answer sheet with worked solutions for the Year 8 algebraic expressions worksheet.
Year 8 Factorising Expressions (Common Factors) Worksheet — Level 2 — Practice Set 3 — Answers
Find the highest common factor of the terms and write it outside the brackets.
1.Factorise fully: 18a + 24b
Answer: 6(3a + 4b)
- Highest common factor: 6
- 18a + 24b = 6(3a + 4b)
- Check by expanding the brackets.
2.Factorise fully: 4x2 + 4x
Answer: 4x(x + 1)
- Highest common factor: 4x
- 4x2 + 4x = 4x(x + 1)
- Check by expanding the brackets.
3.Factorise fully: 18m + 15n
Answer: 3(6m + 5n)
- Highest common factor: 3
- 18m + 15n = 3(6m + 5n)
- Check by expanding the brackets.
4.Factorise fully: 15x2 − 27x
Answer: 3x(5x − 9)
- Highest common factor: 3x
- 15x2 − 27x = 3x(5x − 9)
- Check by expanding the brackets.
5.Factorise fully: 25a + 35b
Answer: 5(5a + 7b)
- Highest common factor: 5
- 25a + 35b = 5(5a + 7b)
- Check by expanding the brackets.
6.Factorise fully: 4x2 + 5x
Answer: x(4x + 5)
- Highest common factor: x
- 4x2 + 5x = x(4x + 5)
- Check by expanding the brackets.
7.Factorise fully: 27x + 9y
Answer: 9(3x + y)
- Highest common factor: 9
- 27x + 9y = 9(3x + y)
- Check by expanding the brackets.
8.Factorise fully: x2 − 8x
Answer: x(x − 8)
- Highest common factor: x
- x2 − 8x = x(x − 8)
- Check by expanding the brackets.
9.Factorise fully: 6m − 21n
Answer: 3(2m − 7n)
- Highest common factor: 3
- 6m − 21n = 3(2m − 7n)
- Check by expanding the brackets.
10.Factorise fully: 6x2 + 18x
Answer: 6x(x + 3)
- Highest common factor: 6x
- 6x2 + 18x = 6x(x + 3)
- Check by expanding the brackets.
11.Factorise fully: 6x + 12y
Answer: 6(x + 2y)
- Highest common factor: 6
- 6x + 12y = 6(x + 2y)
- Check by expanding the brackets.
12.Factorise fully: 6x2 + 27x
Answer: 3x(2x + 9)
- Highest common factor: 3x
- 6x2 + 27x = 3x(2x + 9)
- Check by expanding the brackets.
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.