To solve an equation in factored form, set each factor equal to 0 and solve each equation. Note that this is not the same as setting x equal to 0. If you substitute the value of 0 into the left side you will get $\displaystyle{\left({5}\cdot{0}+{6}\right)}{\left({3}\cdot{0}-{6}={\left({6}\right)}{\left(-{6}\right)}=-{36}\right.}\usepackage{cmbright}\Huge\$ , not 0. So $\displaystyle{x}={0}\usepackage{cmbright}\Huge\$ is not a solution.