Group Factorisation

Recall that in algebraic expansion, we learnt that:

(a + b)(c + d) = ac + ad + bc + bd

This is illustrated in the diagram where (a + b) is the length and (c + d) is the breadth of the rectangle. We can see that the area can be divided into 4 pieces: ac + ad + bc + bd.

In factorisation, we take the 4 terms (ac + ad + bc + bd) and work out the factors (a + b) and (c + d).