Question

已知集合M=｛a², a+1,-3｝, N=｛a-3, 2a-1, a²+1｝, 若M∩N=｛-3｝, 则a的是                                                    
(     )
A  -1         B   0            C   1             D   2

Answer 1

A

M∩N=｛-3｝ N=｛a-3, 2a-1, a²+1｝
若a-3=-3, 则a=0,此时M="{0,1,-" 3}   ,N="{-" 3,- 1,1} 则 M∩N=｛-3,1｝故不适合
若2a-1=-3,则a=" -" 1,此时M="{1," 0,- 3}, N="{-" 4,- 3, 2}
若a²+1=-3,此方程无实数解