About mathematical induction~(10分)急!

Please refer to the solution below:

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let "8^n+2x7^n+6 is divisible by 7" beS(n)
8^1+2*(7^1)+6=28=4*7 is divisible by 7
therefore S(1) is true

Assume S(k)is true
i.e. 8^k+2(7^k)+6 =7M where M is an integer
Consider
8^(k+1)+2(7^(k+1))+6
=8(8^k)+2(7(7^k))+6
=7(8^k)+12(7^k)+7M
=7(8^k+M)+12(7^k) (8^k+M)is an integer

also 12(7^k) is divisible by 7
therefore S(k+1) is true

by M.I. 8^n+2x7^n+6 is divisible by 7 for all +ve integers

2008-08-05 20:28:27 補充：
仲咩今日次次慢過人><"
好唔開心lo~
唔係最快..又冇左最佳

2008-08-05 20:29:31 補充：
上面哥哥可以讓下我呢個小學級嗎?