Dr.tsegay

The 3rd term of arthmetic sequence is 3/4th of 6th term.and their sum is 60.find a,d and nth term.

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  1. a + 2 d = (3/4)[ a + 5d ]
    and
    2 a + 7 d = 60

    ------------------------
    (1/4 a -7/4 d = 0
    or
    1 a - 7 d = 0
    2 a + 7 d = 60
    ------------------- add
    3 a = 60
    a = 20
    d = 20/7

    an = 20 + (n-1)(20/7)

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