If the" n"th term of an AP is (2n+1) then find sum of first" n" term o

1.	If the" n"th term of an AP is (2n+1) then find sum of first" n" term of the AP
Answer» Put n=121+1=3This implies a=3Put n=222+1=5a\'=5So, d=a\'-a=5-3d=2Sum=n/2(2a+(n-1)d)Substitute the valuesn/2(23+(n-1)2)n/22(3+n-1)n(n+2) Answer::---n(n+2)

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