向量组`\alpha _1 = (1,1,1),\alpha _2 = (2,3,4),\alpha _3 = (3,5,7),\alpha _4 = (4,7,11)`的一个最大线性无关组是( )
A. `\alpha _1,\alpha _2,\alpha _3`;
B. `\alpha _2,\alpha _3,\alpha _4`;
C. `\alpha _3,\alpha _4,\alpha _1`;
D. `\alpha _1,\alpha _2,\alpha_3,\alpha _4`.
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若向量`\beta`能由向量组`\alpha _1,\alpha _2, \cdots ,\alpha _s`线性表示,下列说法正确的是( )
A. 存在一组不全为零的数`k_1,k_2, \cdots ,k_s`使得`\beta = k_1\alpha _1 + k_2\alpha _2 + \cdots + k_s\alpha _s`成立;
B. 存在一组全为零的数`k_1,k_2, \cdots ,k_s`使得`\beta = k_1\alpha _1 + k_2\alpha _2 + \cdots + k_s\alpha _s`成立;
C. 存在一组数`k_1,k_2, \cdots ,k_s`使得`\beta = k_1\alpha _1 + k_2\alpha _2 + \cdots + k_s\alpha _s`成立;
D. 对`\beta`的线性表达式唯一。
设向量组\[{\alpha _1} = \left( {\begin{array}{*{20}{c}} a\\ 0\\ c \end{array}} \right),{\alpha _2} = \left( {\begin{array}{*{20}{c}} b\\ c\\ 0 \end{array}} \right),{\alpha _3} = \left( {\begin{array}{*{20}{c}} 0\\ a\\ b \end{array}} \right)\]线性无关,则`a,b,c`必满足( )
A. `a+b+c=0;`
B. `a+b+c\ne0;`
C. `abc=0;`
D. `abc\ne0.`
设向量组\[{\alpha _1} = \left( {\begin{array}{*{20}{c}} {1 + \lambda }\\ 1\\ 1 \end{array}} \right),{\alpha _2} = \left( {\begin{array}{*{20}{c}} 1\\ {1 + \lambda }\\ 1 \end{array}} \right),{\alpha _3} = \left( {\begin{array}{*{20}{c}} 1\\ 1\\ {1 + \lambda } \end{array}} \right)\]的秩为2,则`\lambda=`( )
A. `3;`
B. `-3;`
C. `0 `或` -3;`
D. `0 `或` 3.`
设三阶矩阵\[A = \left( {\begin{array}{*{20}{c}} 1&2&{ - 2}\\ 2&1&2\\ 3&0&4 \end{array}} \right)\]向量`\alpha =(a,1,1)^T`,且满足`A\alpha `与`\alpha`线性相关,则`\alpha=`( )
A. `-1;`
B. `-2;`
C. `-3;`
D. `-4.`