Question

How do you factor `36x^3-9x`?

Answer 1

`9x(2x-1)(2x+1)`

Explanation:

Note that `4xx9=36`

`=>9x(4x^2-1)`

Consider the standard form of `" "a^2-b^2=(a-b)(a+b)`

Note that `4x^2 -> (2x)^2" and " 1=1^2`

`9x[ (2x)^2-1^2]`

`9x(2x-1)(2x+1)`