Question

How do you factor `3x^9-9x^7`?

Answer 1

Given `3x^9-9x^7`

Extract the common factor `3x^7`

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

Treat `3` as `(sqrt(3))^2` for the difference of squares

`= (3x^7)(x+sqrt(3))(x+sqrt(3))`