You probably recognized that $\displaystyle{a}={1},{b}={5}\usepackage{cmbright}\Huge\$ , and $\displaystyle{c}={2}\usepackage{cmbright}\Huge\$ , but mistakenly computed $\displaystyle{{b}}^{{2}}+{4}{a}{c}\usepackage{cmbright}\Huge\$ under the radical. Use the Quadratic Formula: $\displaystyle{x}=\frac{{-{b}\pm\sqrt{{{{b}}^{{2}}-{4}{a}{c}}}}}{{{2}{a}}}\usepackage{cmbright}\Huge\$