You probably factored correctly to get $\displaystyle{9}{x}{\left({x}+{3}\right)}={0}\usepackage{cmbright}\Huge\$ , but then solved $\displaystyle{x}+{3}={0}\usepackage{cmbright}\Huge\$ incorrectly. When you are solving equations, you must add the same number to both sides, or subtract the same number from both sides. The correct answer is $\displaystyle{x}={0}\usepackage{cmbright}\Huge\$ or $\displaystyle{x}=-{3}\usepackage{cmbright}\Huge\$ .