Incorrect. Try substituting some values in for k to test the truthfulness of the statement. If $\displaystyle{k}={5}\usepackage{cmbright}\Huge\$ , does $\displaystyle{{\left(\sqrt{{{k}}}\right)}}^{{2}}\ge{0}\usepackage{cmbright}\Huge\$ ? What about when $\displaystyle{k}=-{5}\usepackage{cmbright}\Huge\$ ?