Question

How do you factor `9x^2 - 49`?

Answer 1

`9x^2 - 49 = (3x)^2 - 7^2`

We know the identity `color(blue)(a^2 - b^2 = (a+b)(a-b)`

`(3x)^2 - 7^2 = color(green)((3x +7)(3x - 7)`