Here is the famous thing, sum of k from 1 to n is n*(n+1)/2.(adsbygoogle = window.adsbygoogle || []).push({});

I'm trying to show this by recurrence equation. Then an is the sum, I have this equation: an=a(n-1)+n. It's not a*(n-1), just like this kind equations n indicates the number of the term.

The charcteristic equation is r^2-r-n=0. I found the roots of r with n in it. Continue solve the coefficients became quite complicated.

Am I doing right? Other good ideas?

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# Homework Help: Recurrence Equation.

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