Answer
$\frac{(13\sqrt 11 - 39)}{2}$
Work Step by Step
$\frac{13}{(3 + \sqrt 11)}$
=$\frac{13\times(3 - \sqrt 11)}{(3 + \sqrt 11)\times(3 - \sqrt 11)}$
=$\frac{(39- 13\sqrt 11)}{3^{2} - \sqrt 11^{2}}$
=$\frac{(39- 13\sqrt 11)}{9 - 11}$
=$\frac{(39- 13\sqrt 11)}{- 2}$
=$\frac{(13\sqrt 11 - 39)}{2}$
