The general term of a sequence is given by an = -4n + 15. Is the sequence an A.P.? If so, find its 15th term and the common difference.

Question

The general term of a sequence is given by an = -4n + 15. Is the sequence an A.P.? If so, find its 15th term and the common difference.

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2 weeks 2021-09-07T05:39:57+00:00 1 Answer 0 views 0

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    2021-09-07T05:41:11+00:00

    an=-4n+15

    put n=1

    a1=-4(1)+15

    a1=11

    put n=2

    a2=-4(2)+15

    a2=7

    put n=3

    a3=-4(3)+15

    a3=3

    if it is an ap then d1 must be equal to d2

    a2-a1=a3-a2

    7-11=3-7

    4=4

    it is an ap

    d=4

    a=11

    a15=a+14d

    a15=11+14(4)

    a15=11+56

    a15=67

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