Correct. The expression can be rewritten as $\displaystyle\frac{{2}}{{{3}{a}}}\cdot\frac{{{a}+{1}}}{{{{a}}^{{2}}+{6}{a}+{9}}}=\frac{{2}}{{{3}{a}}}\cdot\frac{{{a}+{1}}}{{{\left({a}+{3}\right)}}^{{2}}}\usepackage{cmbright}\Huge\$ . When $\displaystyle{a}={0}\usepackage{cmbright}\Huge\$ or $\displaystyle{a}=-{3}\usepackage{cmbright}\Huge\$ , the denominator of the expression becomes 0. These values must be excluded from the domain of the expression.