• 试题 ID 25028


判断下列等式何时成立:
(1)$| \alpha + \beta |=| \alpha - \beta |$ ,
(2)$| \alpha + \beta |=| \alpha |+| \beta |$ ,
(3)$| \alpha + \beta |=| \alpha |-| \beta |$ ,
(4)$\frac{ \alpha }{| \alpha |}=\frac{ \beta }{| \beta |}$ .
A
B
C
D
E
F
答案:

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解析:

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