jmc

Lana defines a function $f(x)$ which is given by the formula $$f(x)=x^2,$$ but only on a domain she has specified which consists of finitely many values $x$; she leaves the function undefined for all other $x$.

Given that the range of $f(x)$ is $\{0,1,2,3,4,5,6,7,8,9\}$, what is the maximum number of points that could be in its domain?