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積に結合法則が成り立つ
作成: 2011-01-13
更新: 2011-01-13
Nの × に結合法則が成り立つ:
a,b,c∈N と Qの単位
u
に対し,
u
×
((a× b) × c)
= (
u
×
(a× b))
×
c
= ( (
u
×
a )
×
b )
×
c
= (
u
×
a )
×
(b× c)
=
u
×
(a× (b × c) )
これより,(a× b) × c = a× (b × c)