Correct. The domain of this expression must exclude $\displaystyle{b}={0}\usepackage{cmbright}\Huge\$ , 2, and -2, since these values would make either the numerator or the denominator of the divisor equal to 0, and would lead to division by 0. Simplifying the expression, you find $\displaystyle\frac{{{b}-{2}}}{{{\left({b}+{2}\right)}{\left({b}-{2}\right)}}}\cdot\frac{{{\left({b}+{2}\right)}{\left({b}-{2}\right)}}}{{b}}=\frac{{{b}-{2}}}{{b}}\usepackage{cmbright}\Huge\$ .