# how to prove the induction problem

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• Apr 1st 2012, 02:36 PM
yingao
how to prove the induction problem
4+8+12+...+4n= 2n(n+1)
• Apr 1st 2012, 02:50 PM
Plato
Re: how to prove the induction problem
Quote:

Originally Posted by yingao
4+8+12+...+4n= 2n(n+1)

Can you show that it is true for $n=1~?$
• Apr 1st 2012, 04:50 PM
yingao
Re: how to prove the induction problem
4n= 2n(n+1)

4 x1 = 2x1 (1+1)

4 = 4
• Apr 1st 2012, 04:54 PM
Plato
Re: how to prove the induction problem
Quote:

Originally Posted by yingao
4n= 2n(n+1)
4 x1 = 2x1 (1+1)
4 = 4

O.K.
Now if we know that for K>1, 4+8+12+...+4K= 2K(K+1) what can say about 4+8+12+...+4K+4(K+1)?
• Apr 1st 2012, 05:20 PM
yingao
Re: how to prove the induction problem
Thanks for your help! I don't know how to go on from here.