Question

How do you factor the expression `9x² - 1`?

Answer 1

`color(blue)((3x+1)(3x-1)`

Explanation:

`9x^2-1`

The above expression can be written as
`(3x)^2 - 1^2`

As per property
`color(blue)(a^2-b^2=(a+b)(a-b)`

So for the given expression
`color(blue)(a=3x`
`color(blue)(b=1`

`(3x)^2 - 1^2= color(blue)((3x+1)(3x-1)`