Fuente TeX:

[\sqrt{x}] = \left\lbrace \begin{array}{ll} \sqrt{x}-1 & \text{ si } \sqrt{x} \in [1,\frac{3}{2}] \\ 2-\sqrt{x} & \text{ si } \sqrt{x} \in [\frac{3}{2},2]\end{array}\right.