Question

1设|A|为三阶行列式,A=（a1,a2,a3)|A|=（）结果为|a1+2a2,a3,a1+a2|不懂啥意思

Answer 1

1.|a1+2a2,a3,a1+a2|

c1-c3

= |a2,a3,a1+a2|

c3-c1

= |a2,a3,a1|

交换列,2次

= |a1,a2,a3|

= |A|.