We can factorise by the method of factoring out the highest common factor, when it is possible to divide every term in an expression by a common factor.
To make it quicker, we will look for the largest common factor, known as the highest common factor (HCF). For example, in the expression 4x + 2 , the HCF is 2.
Factorisation using the HCF Find the HCF for all terms.
1 3 2 Write the HCF in a set of brackets. Divide each term by the HCF and write the answers into a second set of brackets.
Worked example 1 Factorise 6 − 27x
Solution
You can verify your answer by expanding the factors and you will get the original expression.