This is a factorization of the given expression, but $\displaystyle{9}{{c}}^{{2}}\usepackage{cmbright}\Huge\$ is not the GCF. You may have subtracted the two exponents to obtain the $\displaystyle{{c}}^{{2}}\usepackage{cmbright}\Huge\$ as part of your common factor. Factor both terms. They have the variable c in common six times, so $\displaystyle{{c}}^{{6}}\usepackage{cmbright}\Huge\$ is part of the GCF.