Excluded values are the values of the variable that result in a denominator equal to 0. The excluded values here are the solutions to the equations $\displaystyle{{x}}^{{2}}-{25}={0}\usepackage{cmbright}\Huge\$ and $\displaystyle{x}+{5}={0}\usepackage{cmbright}\Huge\$ . The number 25 is not a solution to either of these equations. The number 5 is not a solution to the equation $\displaystyle{x}+{5}={0}\usepackage{cmbright}\Huge\$ , but it is a solution to $\displaystyle{{x}}^{{2}}-{25}={0}\usepackage{cmbright}\Huge\$ .