how to prove the induction problem

4+8+12+...+4n= 2n(n+1)

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Originally Posted by yingao

4+8+12+...+4n= 2n(n+1)

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Can you show that it is true for

4n= 2n(n+1)

4 x1 = 2x1 (1+1)

4 = 4

Quote:

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Originally Posted by yingao

4n= 2n(n+1)
4 x1 = 2x1 (1+1)
4 = 4

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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)?

Thanks for your help! I don't know how to go on from here.