You probably correctly substituted $\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\$ , but made a mistake when simplifying the answer. You cannot combine the real and imaginary terms into one term.