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平面向量数量积的意义

> 下列命题正确的是（　　） A．已知 a ， b ， c 是非零向量，则（ a • b ）• c = a •( b • c ) B．已知 a ， b 是非零向量，则（ a • b ）2= a 2• b 2 C．已知z是复数，且z2＜0，则z是纯虚数 D．已知z是复数，则z2=|z|2

问题：

发布时间：2024-09-08

下列命题正确的是（　　）

A．已知

a

，

b

，

c

是非零向量，则（

a

•

b

）•

c

=

a

•(

b

•

c

)

B．已知

a

，

b

是非零向量，则（

a

•

b

）²=

a

2•

b

2

C．已知z是复数，且z²＜0，则z是纯虚数

D．已知z是复数，则z²=|z|²

参考答案：

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下列命题正确的是（ ） A．已知 a ， b ， c 是非零向量，则（ a • b ）• c = a •( b • c ) B．已知 a ， b 是非零向量，则（ a • b ）2= a 2• b 2 C．已知z是复数，且z2＜0，则z是纯虚数 D．已知z是复数，则z2=|z|2

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