Question

Factorise completely M²-n²

Answer 1

(a+b)(a-b) = a² - b².

[ Proof :

(a+b)(a-b) = a(a-b) +b(a-b)

               = a² - ab + ba - b²

               = a² - ab - ab - b²

               = a² - b².]

Similarly M²-n² = (M+n)(M-n)