Sum of series: 1+2+3+ tnis (A) n(n+1) 2 (B) n(n+1) (C) (n+1)(n+2) 2​

Question

Sum of series: 1+2+3+
tnis
(A)
n(n+1)
2
(B) n(n+1)
(C)
(n+1)(n+2)
2​

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Harper 1 week 2021-09-12T17:20:26+00:00 1 Answer 0 views 0

Answers ( )

    0
    2021-09-12T17:21:56+00:00

    Answer:

    Here, a=1 , d=2-1=1

    \sf{S_{n}=\dfrac{n}{2}[2a+(n-1)d]}

    \sf{S_{n}=\dfrac{n}{2}[2+(n-1)]}

    \sf{S_{n}=\dfrac{n}{2}[n+1]}

    \sf{S_{n}=\dfrac{n^{2}+n}{2}}

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