5+73+7\frac{5 + \sqrt{7}}{3 + \sqrt{7}}3+75+7
multiply the denominator and the numerator by the conjugate of 3 + 7\sqrt{7}7 → 3 - 7\sqrt{7}7
5+73+7\frac{5 + \sqrt{7}}{3 + \sqrt{7}}3+75+7 x 3−73−7\frac{3 - \sqrt{7}}{3 - \sqrt{7}}3−73−7
15−57+37−732−(7)2\frac{15 - 5\sqrt{7} + 3\sqrt{7} - 7}{3^2 - (\sqrt{7})^2}32−(7)215−57+37−7
8−279−7\frac{8 - 2\sqrt{7}}{9 - 7}9−78−27 = 8−272\frac{8 - 2\sqrt{7}}{2}28−27
= 4 - 7\sqrt{7}7
