# The hardness of solving $x^2=2$

What's the hardness of the following problem: $$\textbf{argmin}_x\{|x^2-2|\}$$.

By analytical calculation, I know the solution is $$\pm \sqrt{2}$$. But I am quite confused about whether it is hard with regarding to its computation complexity.

What's the hardness of the following problem: $$\textbf{argmin}_x\{|x^2-2|\}$$.
It is $$O(1)$$. There is a single answer: $$x = \sqrt{2}$$. That means that, regardless of how that answer is represented, a computer can just output the answer and it solves your problem.