Question

10. श्रेणी 1-2 +3-
4+5-6+...nपदों तक का योगफल ज्ञात कीजिए।
Find the sum of the series1-2+3-4+5-6+ ... n terms.​

Answer 1

1–2+3–4+5–6+7−…..  

=(1+3+5+7+….)−(2+4+6+8+….)  

=(1+3+5+7+….)−2(1+2+3+4+….)  

The sum of the following series

=n2–2(n(n+1)/2)  

=n2−(n2–1)  

=n2−n2–1  

=−1

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