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In an AP the first term is 2 and the nth term is 29 and the sum of the n term is 155 find n

  • maths -

    we know that 2+(n-1)d = 29, so
    d = 27/(n-1)

    sum of first n terms is

    n/2 (4+(n-1)d)
    n/2 (4+(n-1)*27/(n-1)) = 155
    n = 10

    check:
    d = 27/9 = 3
    10th term is 2+9(3) = 29
    S10 = 5(4+9(3)) = 155

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