方程的全部解有：A:1, 3, 1.7321, -1.7321 B:1, 3, 1.8523, -1.8321 C:1i, 3i, 1.5684, -1.5985 D:1, 3, 1.8521i, -1.8521i 答案: 1, 3, 1.7321, -1.7321