The 5 Rules of Algebraic Expansion and Factorisation

Rule 1

a (b + c) = ab + ac

Rule 2

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

Rule 3

(a+b) (a+b) = a² + 2ab + b²

Rule 4

(a-b) (a-b) = a² - 2ab + b²

Rule 5

(a+b) (a-b) = a² - b²