三个相邻奇数的乘积一定能被3整除

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三个相邻奇数的乘积一定能被3整除

三个相邻奇数的乘积一定能被3整除
三个相邻奇数的乘积一定能被3整除

三个相邻奇数的乘积一定能被3整除
(2n-1)(2n+1)(2n+3) is divisible by 3
n=1
1(3)(5)= 3(5) is divisible by 3
Assume p(k) is true
(2k-1)(2k+1)(2k+3)=3m
for n=k+1
LS
=(2k+1)(2k+3)(2k+5)
=(2k+1)(2k+3)(2k-1 + 6)
=(2k-1)(2k+1)(2k+3) + 6(2k+1)(2k+3)
= 3m +6(2k+1)(2k+3)
=3[ m + 2(2k+1)(2k+3) ] is divisible by 3
By principle of MI,it is true for all n
=> 三个相邻奇数的乘积一定能被3整除