$\displaystyle{z}=-{7}\usepackage{cmbright}\Huge\$ and $\displaystyle{z}={4}\usepackage{cmbright}\Huge\$ ; domain all z, $\displaystyle{z}\ne{1}\usepackage{cmbright}\Huge\$ , $\displaystyle-{1}\usepackage{cmbright}\Huge\$ , and $\displaystyle\frac{{1}}{{4}}\usepackage{cmbright}\Huge\$