$\displaystyle{{x}}^{{3}}\usepackage{cmbright}\Huge\$ is not a factor of $\displaystyle{42}{x}{{y}}^{{3}}\usepackage{cmbright}\Huge\$ , so $\displaystyle{6}{{x}}^{{3}}{{y}}^{{4}}\usepackage{cmbright}\Huge\$ is not a common factor of the given terms.