Resposta :
(Raiz de 11 + raiz de 7) . (Raiz de 11 + raiz de 7) =
( raiz de 11 - raiz de 7 ) ( raiz de 11+ raiz de 7 )
(raiz de 11)^2 + 2.(raiz de(11.7) +( raiz de 7)^2
(raiz de 11)^2 - ( raiz de 7)^2
11 + 7 + 2.(raiz de 77) => 18 + 2.(raiz de 77)
11 - 7 4
[tex]\frac {\sqrt{11} + \sqrt{7}}{\sqrt{11} - \sqrt{7}} = \frac {\sqrt{11} + \sqrt{7}}{\sqrt{11} - \sqrt{7}} \times \frac {\sqrt{11} + \sqrt{7}}{\sqrt{11} + \sqrt{7}} = \frac {(\sqrt{11} + \sqrt{7})^2}{\sqrt{11}^2 - \sqrt{7}^2 } = \frac{11 + 2\sqrt77 + 7}{11 - 7} = \frac{18 + 2 \times \sqrt77}{4} \\ =\frac{ 9 + \sqrt 77}{2}[/tex]