Find the sum of odd integers from 1to 2001

1.	Find the sum of odd integers from 1to 2001
Answer» AP=1,3,5,7-------2001a=1,d=2,an=2001find sn=?as,an=a+(n-1)d2001=1+(n-1)22001=1+2n-22001+1=2n2002=2nn=1001now,sn=n/2[2a+(n-1)d]=1001/2[2×1+(1001-1)2]1001/2×2[1+1001-1]1001×10011002001

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