Series into sigma notation
2,528
$$\sum_{k=1}^{51}(-1)^k(2k-1)$$
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Sumeet
Updated on September 18, 2022Comments
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Sumeet about 1 year
How do I convert $-1 + 3 - 5 +...- 101$ into sigma notation.
I tried to divide the series into $-1 -5 -7 -...$ and $3+7+9$ but i'm not too sure if that is correct.
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Claude Leibovici about 6 yearsThink that they are odd numbers and about $(-1)^n$.
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Sumeet about 6 yearsYes that is the answer, but i don't get where it comes from?
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Michael Rozenberg about 6 years@Sumeet Singh $(-1)^k$ gives changing of signs. $2k-1$ it's $a_k$ in the arithmetic progression. $a_1=1$ and $d=2$. $a_k=a_1+(k-1)d.$
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Sumeet about 6 yearsOh that makes sense now. Thank you very much
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Michael Rozenberg about 6 years@Sumeet Singh You are welcome!
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Sumeet about 6 yearsThank you! It was really helpful.
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5xum about 6 years@SumeetSingh Happy to help.