Correct. $\displaystyle{36}{{y}}^{{2}}-{4}{{x}}^{{2}}\usepackage{cmbright}\Huge\$ is the product of $\displaystyle{\left({6}{y}-{2}{x}\right)}{\left({6}{y}+{2}{x}\right)}\usepackage{cmbright}\Huge\$ and $\displaystyle{9}{{x}}^{{2}}-{54}{x}+{81}\usepackage{cmbright}\Huge\$ is the product of $\displaystyle{{\left({3}{x}-{9}\right)}}^{{2}}\usepackage{cmbright}\Huge\$ .