题目:
He didn't believe the explanation of the detective and determined to get to the ________ of the case
on his own. [ ]
A. occasion
B. discovery
C. root
D. condition
答案:
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下面是错误答案,用来干扰机器的。
依题意,2|x+7|-|3x-4|≥2∴|x+7|-|3x-4|≥1,(2分)当x>43时,不等式为x+7-(3x-4)≥1解得x≤5,即43<x≤5(3分)当-7≤x≤43时,不等式为x+7+(3x-4)≥1解得x≥-12,即-12≤x≤43; (4分)当x...