You may have miscalculated the discriminant $\displaystyle{{b}}^{{2}}-{4}{a}{c}\usepackage{cmbright}\Huge\$ . If the discriminant were zero, there would be one real solution. You need to rewrite the equation as $\displaystyle{{x}}^{{2}}-{x}-{1}={0}\usepackage{cmbright}\Huge\$ . In this equation: $\displaystyle{a}={1},{b}=-{1}\usepackage{cmbright}\Huge\$ , and $\displaystyle{c}=-{1}\usepackage{cmbright}\Huge\$ .