The solution to this compound inequality is $\displaystyle{a}\ge-{2}\usepackage{cmbright}\Huge\$ and $\displaystyle{a}\le{1}\usepackage{cmbright}\Huge\$ . You may not have noticed that the graph on the number line does not include either of the values $\displaystyle-{2}\usepackage{cmbright}\Huge\$ and 1, so the correct solution must not include these values either.