Correct. The expression can be rewritten as $\displaystyle\frac{{{9}{a}}}{{{a}+{1}}}\cdot\frac{{{a}+{1}}}{{{{a}}^{{2}}-{4}}}=\frac{{{9}{a}}}{{{a}+{1}}}\cdot\frac{{{a}+{1}}}{{{\left({a}+{2}\right)}{\left({a}-{2}\right)}}}\usepackage{cmbright}\Huge\$ . When $\displaystyle{a}=-{1}\usepackage{cmbright}\Huge\$ , $\displaystyle{a}={2}\usepackage{cmbright}\Huge\$ , or $\displaystyle{a}=-{2}\usepackage{cmbright}\Huge\$ , the denominator of the expression becomes 0. These values must be excluded from the domain of the expression.