How do you factor the expression $9x^2-1$ ?

Question

14007 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-01-13T16:24:37

$color(blue)((3x+1)(3x-1)$ is the factorised form of the expression

$9x^2 -1$

The expression can be written as :
$(3x)^2 -1^2$

This is of the form
$color(blue)(a^2-b^2 = (a+b)(a-b)$

Applying the same:
$(3x)^2 -1^2 = color(blue)((3x+1)(3x-1)$

How do you factor the expression 9x^2-19x^2-1?