$\displaystyle{z}={2}\usepackage{cmbright}\Huge\$ and $\displaystyle{z}=-{3}\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$ ; domain all z, $\displaystyle{z}\ne\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$ and $\displaystyle-\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$