Substitute $\displaystyle{a}={1},{b}={2}\usepackage{cmbright}\Huge\$ , and $\displaystyle{c}={2}\usepackage{cmbright}\Huge\$ into the Quadratic Formula: $\displaystyle{x}=\frac{{-{b}\pm\sqrt{{{{b}}^{{2}}-{4}{a}{c}}}}}{{{2}{a}}}\usepackage{cmbright}\Huge\$

$\displaystyle{x}=\frac{{-{2}\pm\sqrt{{{{2}}^{{2}}-{4}{\left({1}\right)}{\left({2}\right)}}}}}{{{2}\cdot{1}}}=\frac{{-{2}\pm\sqrt{{{4}-{8}}}}}{{2}}=\frac{{-{2}\pm\sqrt{{-{4}}}}}{{2}}\usepackage{cmbright}\Huge\$

$\displaystyle=\frac{{-{2}\pm{2}{i}}}{{2}}=\frac{{-{2}}}{{2}}\pm\frac{{2}}{{2}}{i}=-{1}\pm{i}\usepackage{cmbright}\Huge\$