$\displaystyle \sqrt{log(x) - 3} = log(x) - 3$

I'm not sure how to solve this. Logically, it would seem to me that $\displaystyle log(x) - 3$ must equal 0 or 1 for $\displaystyle \sqrt{log(x) - 3}$ to equal $\displaystyle log(x) - 3$. I'm not sure how to prove it though. Could someone point me in the right direction?