I have a rather simple question, but my rusty brain needs a good, swift kick-start.(adsbygoogle = window.adsbygoogle || []).push({});

I start with:

[tex]\sum_{i=1}^k i[/tex]

and substitute in [tex]i=k-j[/tex] to get:

[tex]\sum_{k-j=1}^k (k-j)[/tex]

How do I get from this to the following?

[tex]\sum_{k-j=1}^k (k-j) \rightarrow \sum_{j=0}^{k-1} (k-j)[/tex]

Thanks in advance for your help.

dogma

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# Summation Question (Properties)

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