This is a factorization of the given expression, but $\displaystyle{14}{c}\usepackage{cmbright}\Huge\$ is not the GCF. You may have thought that you needed only to factor out the different factors that occur. However, they have the variable c in common four times, so $\displaystyle{{c}}^{{4}}\usepackage{cmbright}\Huge\$ is part of the GCF.