(1) 绝对值≥，而和为0，则二者皆为0
a = 12, b = -6
(2)
t秒时，A的位置为 a= 12 - 3t; B的位置为 b = -6 - t
a = b, 12 - 3t = -6 - t
t = 9
a = b = 15 (应为C对应的数)
(3) b = -6 - t
M: m = (-6 - t + 0)/2 = -(t + 6)/2
N: n = (-6 - t + 12)/2 = (6 - t)/2
MN = n - m = (6 - t)/2 - [-(t + 6)/2] = 6
不变
内容全部来源于网络收集，如有侵权，请联系网站删除：QQ：24596024