Incorrect. Factor the numerator and denominator separately and then look for common terms. Notice that $\displaystyle{4}{{x}}^{{2}}-{144}={4}{\left({{x}}^{{2}}-{36}\right)}\usepackage{cmbright}\Huge\$ , and $\displaystyle{2}{{x}}^{{2}}-{24}{x}+{72}={2}{\left({{x}}^{{2}}-{12}{x}+{36}\right)}\usepackage{cmbright}\Huge\$ . Does this help you simplify the expression?