\frac{(3 + \sqrt7)(1 + \sqrt7)}3(1 - 7) = \frac{3(1) + 3\sqrt7 + \sqrt7 + 7}3(-6) = \frac{10 + 4\sqrt7}-18 = -\frac{10 + 4\sqrt7}18 = -\frac{5 + 2\sqrt7}9. - Dyverse