Question

已知A=(x1,x2,x3),其中x1,x2,x3为三维列向量,且|A|=4,求|B|=|x1,3x1加2x2,2x3)

Answer 1

|B| = |x1,3x1+2x2,2x3|

= |x1,2x2,2x3|

= 4|x1,x2,x3|

= 4|A|

= 16.