Question

$(a-b)(a+b)$ is the factorised form of :

• A. $a^2-ab+b^2$
• B. $a^2-b^2$
• C. ${(a-b)}^2$
• D. ${(a+b)}^2$

Answer 1

Answer: (B)

$a^2-b^2$

$(a-b)(a+b)=a(a+b)-b(a+b)$
$=a^2+ab-ab-b^2$
$=a^2-b^2$