# How do you simplify 12 - 6 sqrt 2?

It's already in simplest form, though you could also write it as $6 \left(2 - \sqrt{2}\right)$ and as $12 - \sqrt{72}$.
The form $6 \left(2 - \sqrt{2}\right)$ comes from factoring and the form $12 - \sqrt{72}$ comes from the fact that $6 \sqrt{2} = \sqrt{36} \sqrt{2} = \sqrt{36 \cdot 2} = \sqrt{72}$.