Incorrect. The expression is being raised to a power of 3, so be sure to multiply -4 by itself 3 times: $\displaystyle-{4}\cdot-{4}\cdot-{4}\usepackage{cmbright}\Huge\$ . You will also want to multiply the quantity $\displaystyle{{a}}^{{2}}\usepackage{cmbright}\Huge\$ by itself 3 times: $\displaystyle{{a}}^{{2}}\cdot{{a}}^{{2}}\cdot{{a}}^{{2}}\usepackage{cmbright}\Huge\$ .