Expansion simply means multiply each of the terms outside the bracket by each of the terms inside the bracket. 3a(a−4b)=3a×a−3a×4b 3a(a−4b)=3a2−12ab Note: Every number is raised to the power 1 but it is not written. Law of multiplication of indices am×an=am+m a×a=a1×a1 a×a=a1+1 a×a=a2 3×4=12