超級易的maths questions (5點分)

2007-04-18 1:15 am

點解( -1 ) x ( -1 )^n-1 = ( -1 )^n 而唔係 ( +1 )^n ???
負負唔係得正咩?

回答 (3)

2007-04-18 1:27 am

✔ 最佳答案

首先,
(-1) = (-1)^1
所以,
(-1) x (-1)^n-1
= (-1)^1 x (-1)^n-1

根據"底數相同, 指數相加"的求積定理,
(-1) x (-1)^n-1
= (-1)^1 x (-1)^n-1
= (-1)^1+n-1
= (-1)^n

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2007-04-18 1:22 am

(-1)(-1^(n-1)) = [(-1)(-1^n) / (-1)] = (-1^n)

由於指數(-1) = 除去該數
所以 (-1^(n-1)) = (-1^n) / (-1)

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2007-04-18 1:20 am

try let a = -1
( -1 ) x ( -1 )^n-1 = ( -1 )^n
=>(a)(a)^n-1=(a)^n

just that simple.

參考: 我路過架咋, 答錯左唔好打我.

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