You probably substituted $\displaystyle\frac{{7}}{{4}}\usepackage{cmbright}\Huge\$ for b and $\displaystyle-{1}\usepackage{cmbright}\Huge\$ for c in the Quadratic Formula. The first step is to add x to both sides:

$\displaystyle{{x}}^{{2}}+{x}+\frac{{7}}{{4}}={0}\usepackage{cmbright}\Huge\$

Now substitute $\displaystyle{a}={1},{b}={1}\usepackage{cmbright}\Huge\$ , and $\displaystyle{c}=\frac{{7}}{{4}}\usepackage{cmbright}\Huge\$ into $\displaystyle{x}=\frac{{-{b}\pm\sqrt{{{{b}}^{{2}}-{4}{a}{c}}}}}{{{2}{a}}}\usepackage{cmbright}\Huge\$