不等式|x+3|-|x-1|≤a2-3a对任意实数x恒成立，则实数a的取值范围为（ ）
A. （-∞，-1]∪[4，+∞）
B. （-∞，-2]∪[5，+∞）
C. [1，2]
D. （-∞，1]∪[2，+∞）
人气：223 ℃ 时间：2019-09-22 08:04:19
解答
因为|x+3|-|x-1|≤4对|x+3|-|x-1|≤a2-3a对任意x恒成立，
所以a2-3a≥4即a2-3a-4≥0，
解得a≥4或a≤-1．
故选A．
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