Question

Which of the following identity can be used to factorise $x^2-4y^2$?

• A.
• B. = (a - b)(a + b)
• C. (x + a)(x + b) =
• D. None of these

Answer 1

The correct option is B

= (a - b)(a + b)

The expression $x^2-4y^2$ can be written as,

$=x^2-(2y{)}^2$

It is in the form of $a^2-b^2$.
So, the identity $a^2-b^2$ = $(a-b)(a+b)$ can be used to factorise $x^2-4y^2$.

$\Rightarrow$ $x^2-4y^2$$=x^2-(2y{)}^2=(x+2\left)\right(x-2)$