# How do you factor completely a^2 - 121b^2?

Nov 14, 2015

color(blue)((a+11b)(a-11b)

#### Explanation:

a^2−121b^2
This expression can be rewritten as (a)^2−(11b)^2

Now, as per the below property,
color(blue)(x^2-y^2=(x+y)(x-y), we can rewrite the expression as:

(a)^2−(11b)^2=color(blue)((a+11b)(a-11b)
(Here, $x = a , y = 11 b$ )

So the factorised form of the expression is:
=color(blue)((a+11b)(a-11b)