(4)设A为三阶矩阵,且 |A|=2, 则 |(({A)^*)}^-1|=() .-|||-A. dfrac (1)(4) B.1 C.2 D.4

若_(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0只有零解，则_(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0必须满足（）A._(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0且_(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0B._(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0且_(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0C._(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0且_(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0D._(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0且_(1)+((k)^2+1)(x)_(2)+2(x)_(3)=0-|||-_(1)+(2k+1)(x)_(2)+2(x)_(3)=0-|||-(x)_(1)+k(x)_(2)+(2k+1)(x)_(3)=0

7.设A为三阶矩阵,已知 |((2A))^-1|=dfrac (1)(2), 则 |A|= __ ;

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若 n 阶 方阵 A 满足^2=A，其中 E 为 n 阶 单位方阵则下列表述中错误的是 ( ) A A 只 能为单位阵 B ^2=AC ^2=AD 如果 A 可逆，则 A 一定为单位阵 E A 可以只经过初等行变换变为单位 矩阵 E

随机事件 A,B 满足 (A)=P(B)=dfrac (1)(2), 且 (Acup B)=1, 则 (overline (A)cup overline (B))= __ .

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