问题 填空题
已知
a
=(3,3,2),
b
=(4,-3,7),
c
=(0,5,1),则(
a
+
b
)•
c
=______.
答案

由于

a
=(3,3,2),
b
=(4,-3,7),则
a
+
b
=(7,0,9)

又由

c
=(0,5,1),则(
a
+
b
)•
c
=(7,0,9)•(0,5,1)=9

故答案为 9

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