Correct. A binomial in the form $\displaystyle{{a}}^{{3}}+{{b}}^{{3}}\usepackage{cmbright}\Huge\$ can be factored as $\displaystyle{\left({a}+{b}\right)}{\left({{a}}^{{2}}-{a}{b}+{{b}}^{{2}}\right)}\usepackage{cmbright}\Huge\$ .

$\displaystyle{{x}}^{{3}}+{27}={{x}}^{{3}}+{{3}}^{{3}}={\left({x}+{3}\right)}{\left({{x}}^{{2}}-{x}\cdot{3}+{{3}}^{{2}}\right)}={\left({x}+{3}\right)}{\left({{x}}^{{2}}-{3}{x}+{9}\right)}\usepackage{cmbright}\Huge\$

The missing constant is 9.