Correct. $\displaystyle-\sqrt{{{81}}}\usepackage{cmbright}\Huge\$ (which can be written as -9) and $\displaystyle{3.0}{\overline{{3}}}\usepackage{cmbright}\Huge\$ are both rational numbers, and $\displaystyle\sqrt{{{2}}}\usepackage{cmbright}\Huge\$ and $\displaystyle\pi\usepackage{cmbright}\Huge\$ are both irrational numbers. The set of real numbers includes both rational and irrational numbers.