Correct. The domain of this expression must exclude $\displaystyle{a}={0}\usepackage{cmbright}\Huge\$ , since this value would make the numerator of the divisor equal to 0: $\displaystyle\frac{{{6}{{\left({0}\right)}}^{{3}}}}{{2}}=\frac{{0}}{{2}}={0}\usepackage{cmbright}\Huge\$ , and would lead to division by 0: $\displaystyle\frac{{{12}{{\left({0}\right)}}^{{5}}}}{{6}}\div{0}\usepackage{cmbright}\Huge\$ . Simplifying the expression, you find $\displaystyle\frac{{{12}{{a}}^{{5}}}}{{6}}\cdot\frac{{2}}{{{6}{{a}}^{{3}}}}=\frac{{{2}{{a}}^{{2}}}}{{3}}\usepackage{cmbright}\Huge\$ .