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guropalica
Sep28-11, 04:53 AM
Proof by induction that 3 * 5^2n+1) + 2^3n+1 is divisible by 17!
Thanks in advance guys

RamaWolf
Sep28-11, 07:48 AM
In your expression, there is an ")" without an "(" --> 3 * 5^2n+1) + 2^3n+1

so it is not clear what do to!

daveb
Sep28-11, 08:01 AM
You also need to try yourself and let us know where you're stuck. Then we can help.

guropalica
Sep28-11, 09:37 AM
I proved the base case n=1, and then I try doing the step case assuming that it satisfies for any k, then I try proving it by k+1.
I got sth like 24 * (3 * 5^(2k+1)) + 7 * 2^(3k +1) Now I'm stuck can't continue, I don't have any ideas :/
btw the initial equation is 3 * 5^(2n+1) + 2^(3n+1) !

guropalica
Sep28-11, 09:58 AM
Got it now :) let's denote the initial statement as K + L, so we have sth like 24l + 7k = 7(k+l) + 17k, sum of two numbers divisible by 17 is divisible by 17, anyway thx