### Resource: Unit 4 Algebra (3)

In S1, you will learn 4 methods to factorise algebraic expressions.
Depending on the characteristics of the expression, you will have to decide on the most appropriate method to carry out factorisation.

The 4 methods are:
• Factorisation by Identifying Common Factor
• Factorisation by Grouping
• Factorisation using Special Products
• Factorisation using Cross Method

Factorisation: Summary (4 methods)

Method 1: Factorisation by Identifying Common Factor(s)

Watch the thinking behind factorisation by identifying common factors

There are altogether 6 examples (similar). Look out for the 'change' of sign.

This playlist consists of 6 examples:
To factorise...
E.g. 1: a (c + d) + b (- c - d)
E.g. 2: m (a + 2d) - n (- a - 2d)
E.g. 3: a (x - y) + b (- x + y)
E.g. 4: 2p (x - 3y) + q (3y - x)
E.g. 5: 3a (2b - 5c) - 5d (- 2b + 5c)
E.g. 6: 3x (1 - 4y) - 4u (4y - 1)

More Examples for Method 1 & Method 2
• Method 1: Factorisation by Identifying Common Factor(s) (Examples 1, 2 & 3)
• Method 2: Factorisation by Special Products (Examples 4, 5 & 6)

Method 2: Factorisation by Grouping
Notice that this method involves identifying common factors twice - at two different stages.

Method 3: Factorisation by Special Products

Click HERE to access the Playlist for the examples of Factorisation using Special Product

Method 4: Factorisation by Cross Method