This quadratic is already written in vertex form. In y = a(x - h)^2 + k, the vertex is (h, k). Be careful with the sign inside the bracket: (x + 1) means h = -1, while (x - 1) means h = 1. Reading the values from y = 3(x - 5)^2 + 6, the vertex is (5, 6). Therefore, the correct answer is (5, 6).