Write as a polynomial:

2 (x-3) (x+3)

Long way:

2 (x-3) (x+3) = 2 (x*x + 3*x - 3*x - 3*3)

2 (x-3) (x+3) = 2 (x^2 - 9)

2 (x-3) (x+3) = 2x^2 - 2*9

2 (x-3) (x+3) = 2x^2 - 18

Shortcut way:

Using formula (x+a) (x-a) = x^2 - a^2, where a = 3, in the case of (x+3) (x-3), so we have

(x+3) (x-3) = x^2 - 9.

Then, we multiply that by 2, which gives 2x^2 - 18.