Tuesday, 25 October 2016

discrete mathematics - Prove that for all positive integers n,9|(11n2n)

Prove that for all positive integers n,9|(11n2n)



So the base case would be



9 * k = (11*1 - 2 * 1)
9 * k = 9

k = 1 so yes


The inductive hypothesis would be the fact that (11n2n) is divisible by 9,



So I thought then I would have to show that (11(n+1)2(n+1)) is divisible by9



11^(n+1) - 2^(n+1)
11^(n) * 11^1 - 2^n * 2^1
(11-2) * (11^n-2^n)

9*(11^n-2^n)


Is this algebraically correct?

No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find limh0sin(ha)h without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...