Re: induction


katy wrote:
> Hi all!! I'm having problems in proof by induction that:
>
> Sum from k=1 to n of k³ = (sum from k=1 to n of k)²
>
>
> Can somebody help me?

Try to avoid special characters, many people won't see them.

Rewriting:

Sum from k=1 to n of k^3 = (sum from k=1 to n of k)^2

I assume you're stuck on the step of showing that being true
for n implies being true for n+1.

Sum from k=1 to n+1 of k^3 = (n+1)^3 + Sum from k=1 to n of k^3

= ? (sum from k=1 to n+1 of k)^2

You know that

Sum from k=1 to n of k^3 = (sum from k=1 to n of k)^2

by assumption, and that

(sum from k=1 to n+1 of k) = (n+1) + (sum from k=1 to n of k)

So where are you stuck?

- Randy

.

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