数字推理-12,2,8,7,3,()
问题描述：
数字推理-12,2,8,7,3,()
答
[(-12) + 8 * 2] / 2 = 2
[2 + 7 * 2] / 2 = 8
[8 + 3 * 2] / 2 = 7
==> [a1 + a3 * 2] / 2 = a2
所以 [7 + * 2] / 2 = 3 求得 = -0.5