Question

How do you factor the expression `9x^2-25`?

Answer 1

`(3x)^2-(5)^2=(3x+5)(3x-5)`

Explanation:

`9x^2-25` fits the form `a^2-b^2`, where `a=3x` and `b=5`. Rewrite the expression as `(3x)^2-(5)^2`.

Use the difference of squares: `a^2-b^2=(a+b)(a-b)`.

`(3x)^2-(5)^2=(3x+5)(3x-5)`