> 数学 >
a
=(1,-2),
b
=(-3,4),
c
=(3,2)则(
a
+2
b
)•
c
=(  )
A. (-15,12)
B. 0
C. -3
D. -11
人气:429 ℃ 时间:2020-05-13 03:13:58
解答
a
+2
b
=(1,-2)+2(-3,4)=(-5,6),
(
a
+2
b
)•
c
=(-5,6)•(3,2)=-3,
故选C
推荐
猜你喜欢
© 2024 79432.Com All Rights Reserved.
电脑版|手机版