It appears that you attempted to simplify the left side of the equation to $\displaystyle{\log{{5}}}{x}\usepackage{cmbright}\Huge\$ . However, $\displaystyle{\log{{2}}}{x}+{\log{{3}}}\usepackage{cmbright}\Huge\$ is not the same as $\displaystyle{\log{{\left({2}{x}+{3}{x}\right)}}}\usepackage{cmbright}\Huge\$ . Instead, you should use the product property to simplify $\displaystyle{\log{{2}}}{x}+{\log{{3}}}\usepackage{cmbright}\Huge\$ .