Maths Library

Factoring polynomials: Grade 9 math

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

Factoring polynomials is taught in Grade 9 (age 14 to 15) as a main teaching focus. 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 Common Core State Standards. Check wording and codes against the official document.

  • Use the structure of an expression to identify ways to rewrite it, such as factoring quadratic and polynomial expressions.
  • Solve quadratic equations in one variable using factoring, square roots, or the quadratic formula.

Sample sheet and answers

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

Factoring polynomials

Grade 9 math

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

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)