Example 1 · level 1
Factorise completely: 8x + 12y
- 2(4x + 6y)
- 4x(2 + 3y)
- 4(2x + 3y)
- 4(2x − 3y)
Show solution
- HCF of the terms = 4.
- Divide each term by it: 2x + 3y.
- So 8x + 12y = 4(2x + 3y).
- Check by expanding the bracket again.
Answer: 4(2x + 3y)
CLASS 8 MATHS · FACTORISATION
Factorise by taking out the common factor
Find the HCF of all the terms (numbers and letters) and take it outside the bracket.
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Worked examples
Example 2 · level 2
Factorise completely: 9x² + 81x
- 9x(x + 9)
- 3x(3x + 27)
- 9(x² + 9x)
- 9x(x − 9)
Show solution
- HCF of the terms = 9x.
- Divide each term by it: x + 9.
- So 9x² + 81x = 9x(x + 9).
- Check by expanding the bracket again.
Answer: 9x(x + 9)
Example 3 · level 3
Factorise completely: 20x²y + 12xy²
- 4xy(5y + 3x)
- 4x(5xy + 3y²)
- 2xy(10x + 6y)
- 4xy(5x + 3y)
Show solution
- HCF of the terms = 4xy.
- Divide each term by it: 5x + 3y.
- So 20x²y + 12xy² = 4xy(5x + 3y).
- Check by expanding the bracket again.
Answer: 4xy(5x + 3y)