Question

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

Answer 1

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

Explanation:

`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)`