• 2022-06-07
    设 \( A \)是 \( 3 \times 3 \)矩阵, \( B \)是 \( 4 \times 4 \)矩阵,且\( \left| A \right| = 1,\,\left| B \right| = - 2, \) 则\( \left| {\left| B \right|A} \right| = \) ______
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    • 0

      设\( A \) 是\( 3 \) 阶矩阵,且\( \left| A \right| = 3 \) ,则 \( \left| { - 3A} \right| = \)( ) A: -9 B: 9 C: -81 D: 81

    • 1

      设\( {\alpha _1} = {\left( {1,2, - a, - 3} \right)^T},{\alpha _2} = {\left( { - 3,2,4,1} \right)^T} \)且\( \left( { { \alpha _1},{\alpha _2}} \right) = - 1 \),则\( a = \)( ) A: \( - {2 \over 3} \) B: \( - {3 \over 4} \) C: \( - {1 \over 4} \) D: \( {1 \over 2} \)

    • 2

      设\( A \)是3阶矩阵,若\( \left| {3A} \right| = 3 \),则\( \left| {2A} \right| = \)( ) A: 1 B: 2 C: \( {2 \over 3} \) D: \( {8 \over 9} \)

    • 3

      (4). 设每年袭击某地的台风次数 \( X\sim P\left( \lambda \right) \),且\( P\left\{ {X=1} \right\}=P\left\{ {X=2} \right\} \),则概率 \(P\left\{ {X=4} \right\} =\)()。

    • 4

      若\( A \)是正交矩阵,则\( \left| A \right| = 1 \)或\( \left| A \right| = - 1 \) .