MATH

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In an arithmetic sequence, the first term is 100 and the sixth term is 85. Find the common difference. Then, find the 50th term of the sequence.

Do I use the formula an=a1+(n-1)d?
If so, what would my "n" by in the equation?

  • MATH -

    The nth term of an arithmetic progression is defined by N = a + (n-1)d where N = the nth term, a = the first term and d = the common difference.

    Therefore,
    85 = 100 + (6 - 1)d
    -15 = 5d making d = -3

    The 50th term then becomes
    N(50) = 85 + (50 - 1)(-3) = ?

  • MATH -

    -402

  • MATH -

    ah what!!!!!!!!!!!!!!!!!!!

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