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Factorising algebraic expressions: Year 9 maths

This topic covers rewriting expressions as products of factors by taking out common terms or factorising quadratics. The worksheet gives structured practise in identifying common factors and factorising trinomials.

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What this covers

Factorising algebraic expressions is taught in Year 9 (age 14 to 15) as a topic to introduce. It sits in the Algebra strand.

Worked example

Factorise fully: x^2 - 5x - 14

  1. Find two numbers that multiply to -14 and add to -5
  2. The factor pairs of -14 include (-7, 2), and -7 + 2 = -5
  3. Write as double brackets: (x - 7)(x + 2)

Answer: (x - 7)(x + 2)

Difficulty scale

The sheet generator offers five difficulty settings for this topic.

  1. Common numerical factor only, e.g., 6x + 9 = 3(2x + 3)
  2. Common algebraic and numerical factor, e.g., 4x^2 - 6x = 2x(2x - 3)
  3. Simple quadratic trinomials x^2 + bx + c with positive terms
  4. Quadratic trinomials x^2 + bx + c involving negative terms
  5. Difference of two squares and quadratics with a > 1, e.g., 2x^2 + 7x + 3

Common mistakes

  • Partially factorising by taking out only a numerical factor when a variable is also common
  • Confusing signs when factorising quadratics with a negative constant term

Curriculum links

Indicative matches to Australian Curriculum v9. Check wording and codes against the official document.

  • AC9M9A02 Expand algebraic expressions, including binomial expansions, and factorise monic quadratic and linear expressions.

Sample sheet and answers

Six questions at the level's usual difficulty. Open the editor to change, add or regenerate any of them.

Factorising algebraic expressions

Year 9 maths

Qs
6
Marks
12
NameDateScore / 12
1.
Factorise 28x + 49.
[2]
2.
Factorise 25x + 30.
[2]
3.
Factorise 36x + 42.
[2]
4.
Factorise 24x + 24.
[2]
5.
Factorise 3x + 6.
[2]
6.
Factorise 4x + 24.
[2]

Answer key

  1. 7(4x + 7)The highest common factor is 7; 7(4x + 7)
  2. 5(5x + 6)The highest common factor is 5; 5(5x + 6)
  3. 6(6x + 7)The highest common factor is 6; 6(6x + 7)
  4. 6(4x + 4)The highest common factor is 6; 6(4x + 4)
  5. 3(x + 2)The highest common factor is 3; 3(x + 2)
  6. 4(x + 6)The highest common factor is 4; 4(x + 6)