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    This is a two part question, can somebody please me work it out:
    3. A sequence a1,a2,a3,....... is defined by
    a1=3
    an+1= 3an-5, n>1

    A. Find the value of a2 and the value of a3
    B. Calculate the value of
    5
    ar
    r=1

    Can somebody please help as the wording has completely thrown me.
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    It means that the first term in the sequence is a_1=3, and each term after that is given by the formula a_{n+1}=3a_n-5. So to get the next term, you multiply the previous term by 3, and then subtract 5.

    a_2 just means the second term, and so on.

    \displaystyle\sum_{r=1}^{5}a_r means the sum of the first five terms.
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    But that would give me this:
    a2= 3(3)-5=4
    a3= 3(4)-5=7

    That looks right but of you do a4:
    a4= 3(7)-5=16

    It all goes wrong there isn't a sequence anymore
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    (Original post by AveUgotaWkdSide)
    a3= 3(4)-5=8
    Well that's not right, is it?

    What you get will be a sequence, even though the numbers won't go up by a fixed amount each time. Don't worry about that.
 
 
 
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