2. (5 分) 已知集合 $A=\{1,2,3\}, B=\{x \mid （ x+1)(x-2)<0, x \in Z\}$, 则 $A \cup B$ 等于 $(\quad)$
Gaokao · Math · previous-year question
- A.$\{1\}$
- B.$\{1,2\}$
- C.$\{0,1,2,3\}$correct
- D.$\{-1,0,1,2,3\}$
Answer
C. $\{0,1,2,3\}$
Explanation
解: $\because$ 集合 $A=\{1,2,3\}$, $B=\{x \mid(x+1) \quad(x-2)<0, x \in Z\}=\{0,1\}$, $\therefore \mathrm{A} \cup \mathrm{B}=\{0,1,2,3\}$. 故选: C.
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