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