下列各组向量中,向量a,b,c共面的一组是()A．a="("4,2,1),b="(–1,"2,2),c="("–1,1;5).B．a="("1,2,–3),b="(–2,"–4,6),c="("1,0,5).C．a="("0,0,1),b="(–

Question

下列各组向量中, 向量a , b, c 共面的一组是  (   )

A．a =" (" 4, 2, 1 ), b =" (–1," 2 , 2 ), c =" (" –1, 1 ; 5 ).

B． a =" (" 1, 2, –3 ), b =" (–2," –4 , 6 ) , c =" (" 1, 0 ,5 ).

C．a =" (" 0, 0, 1 ), b =" (–1," 0 , 0 ), c =" (" 0, –1 ; 0 ).

D．a =" (" –2, 3, 1 ), b =" (3," –2 , –2 ), c =" (" –1, 0 ; 2 ).

Answer 1

B

对于选项B，∵(–2, –4 , 6 )=" -2" ( 1, 2, –3 )，∴b =-2a，即向量a 与b 共线，所以a =" (" 1, 2, –3 ), b =" (–2," –4 , 6 ) , c =" (" 1, 0 ,5 )共面，故选B