Factorising Linear Expressions

  • EDEXCEL GCSE
  • AQA GCSE
  • OCR GCSE
  • EDUQAS GCSE

Video masterclass

Topic summary

Factorising is the opposite of expanding. When we factorise we are putting an expression into a bracket. We find the largest term we can divide out from all terms and put that outside the bracket.

You could factorise just with numbers.

\[ 15 + 20 \]

To factorise this expression, you look for common factors in the terms. Both are in the 5 times table.

\[ 15 + 20 = 5(3 + 4) \]

How to factorise

\[6x + 12\]

Identify the common factor. 6x and 12 can both be divided by 6. 6 will be outside the bracket.

\[ 6( \ \ \ \ \ \ \ ) \]

Divide 6x and 12 by 6 to find our terms inside the bracket.

\[ 6(x + 2) \]

Harder factorising

\[14ab + 21a\]

Identify the common factor. 14ab and 21a can both be divided by 7, but also by a. 7a will be outside the bracket.

\[ 7a( \ \ \ \ \ \ \ ) \]

Divide 14ab and 21a by 7a to find our terms inside the bracket.

\[ 7a(2b + 3) \]

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