$\displaystyle{18}{{x}}^{{2}}{{y}}^{{3}}{\left({1}+{{x}}^{{2}}{y}\right)}={18}{{x}}^{{2}}{{y}}^{{3}}+{18}{{x}}^{{4}}{{y}}^{{4}}\ne{18}{{x}}^{{2}}{{y}}^{{3}}+{14}{{x}}^{{4}}{{y}}^{{4}}\usepackage{cmbright}\Huge\$ , so this factorization is incorrect.