All x, $\displaystyle{x}\ne-{2}\usepackage{cmbright}\Huge\$ and $\displaystyle{x}\ne{6}\usepackage{cmbright}\Huge\$ , and all y, $\displaystyle{y}\ne{5}\usepackage{cmbright}\Huge\$ and $\displaystyle{y}\ne-{1}\usepackage{cmbright}\Huge\$