[tex] \sqrt{7} ( \sqrt{6} + 1) - \sqrt{6 }( \sqrt{7} + 1) = \frac{1}{ \sqrt{7} + \sqrt{6} } \\ \sqrt{42} + \sqrt{7} - \sqrt{42} - \sqrt{6} = \frac{1}{ \sqrt{7} + \sqrt{6} } \\ \sqrt{7} - \sqrt{6} = \frac{1}{ \sqrt{7} + \sqrt{6} } (inmultim \: \\ cu \frac{ \sqrt{7} - \sqrt{6} }{ \sqrt{7} - \sqrt{6} }) < = > \sqrt{7} - \sqrt{6} = \sqrt{7} - \sqrt{6} [/tex]
