You may have correctly factored $\displaystyle\sqrt{{{48}}}\usepackage{cmbright}\Huge\$ as $\displaystyle\sqrt{{{3}}}\cdot\sqrt{{{{4}}^{{2}}}}\usepackage{cmbright}\Huge\$ , but while taking the square root of $\displaystyle{{4}}^{{2}}\usepackage{cmbright}\Huge\$ , you mixed up the places of 4 and 3.