Correct. If $\displaystyle\sqrt{{{x}+{4}}}-{1}={8}\usepackage{cmbright}\Huge\$ , then $\displaystyle\sqrt{{{x}+{4}}}={9}\usepackage{cmbright}\Huge\$ , so $\displaystyle{{\left(\sqrt{{{x}+{4}}}\right)}}^{{2}}={{9}}^{{2}}\usepackage{cmbright}\Huge\$ . Therefore $\displaystyle{x}+{4}={81}\usepackage{cmbright}\Huge\$ , so $\displaystyle{x}={77}\usepackage{cmbright}\Huge\$ .