Incorrect. Substitute each value of y into the expression. Use the correct order of operations: first calculate $\displaystyle{{y}}^{{3}}\usepackage{cmbright}\Huge\$ and $\displaystyle{{y}}^{{2}}\usepackage{cmbright}\Huge\$ , then multiply $\displaystyle{{y}}^{{2}}\usepackage{cmbright}\Huge\$ by 2, and then subtract.