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    Buying Whizz kid!@!
    Topic Started: Jun 11 2012, 08:56 PM (184 Views)
    TheTankProd
    Zapdos
    okay i'm not dumb or anything because i did this before but my fuckin teacher lost my work so now i have to re-do it 3 months later now i've forgotten, so wondering if anyone in DV is a bamf and can help me out, ill list the questions below, only 3 questions so nothing too much :P


    Arithmetic Series
    ----------------
    the nth term is a+(n-1)d
    the sum (or total) of n terms is n/2{2a+(n-1)d)

    Geometric Series
    ----------------
    nth term = arn-1
    sum of n terms = a(1-rN)/1-r




    1) find the 8th term of each of these sequences

    a) 2,5,8,11
    b) 3,7,11,15
    c) 2,10,50,250
    d) 2,6,18,54


    2) find the sum of the first 10 terms of the following series

    a)3,8,13,18
    b)1,3,9,27

    3) the first term of an arithmetic series is 1. the common difference is 6 find the 10th term of the series, the sum of the first N terms is 7400 find N


    if anyone can help me with this ill be greatly appreciated and i'll owe you one big time ;)
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    Rune
    Member Avatar
    Zapdos
    yah i slept though hs math
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    Billy
    Member Avatar
    Kangaskhan
    1) find the 8th term of each of these sequences (Nth term) - a = first term d= common difference

    a) 2,5,8,11 a =2 d=3 Nth term = a+(n-1)d = 2+(8-1)3 = 23 arithmetic
    b) 3,7,11,15 = 3+(8-1)4 =31 arithmetic

    Geometric a= first term r = common factor
    c) 2,10,50,250 a=2 r=5 ar^(n-1) 2*5^7 = 156250

    d) 2,6,18,54 a=2 r=3 ar^(n-1) 2*3^7 = 4374


    2) find the sum of the first 10 terms of the following series

    a)3,8,13,18 arithmetic 10/2(6+(10-1)*5) =255
    b)1,3,9,27 geometric a=1 r=3 (1(1-3^10))/(1-3) = 29524

    3) the first term of an arithmetic series is 1. the common difference is 6 find the 10th term of the series, the sum of the first N terms is 7400 find N

    a=1 d=6 10th term - a+(n-1)d = 1+(10-1)6 = 55 = 10th term
    Sn=7400 n/2(2+(n-1)6)=7400
    3n^2n-12n-7400=0
    n=50 n=-49.3333

    n cannot be negative therefore n=50

    :D

    Edited by Billy, Jun 12 2012, 09:19 AM.
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    TheTankProd
    Zapdos
    dude! i love you FULL HOMO!
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    Nico
    Member Avatar
    KFC King
    so playing runescape is now proven to be beneficial to education!
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    Deleted User
    Deleted User

    TheTankProd
    Jun 11 2012, 08:56 PM
    okay i'm not dumb or anything because i did this before but my fuckin teacher lost my work so now i have to re-do it 3 months later now i've forgotten, so wondering if anyone in DV is a bamf and can help me out, ill list the questions below, only 3 questions so nothing too much :P


    Arithmetic Series
    ----------------
    the nth term is a+(n-1)d
    the sum (or total) of n terms is n/2{2a+(n-1)d)

    Geometric Series
    ----------------
    nth term = arn-1
    sum of n terms = a(1-rN)/1-r




    1) find the 8th term of each of these sequences

    a) 2,5,8,11
    b) 3,7,11,15
    c) 2,10,50,250
    d) 2,6,18,54


    2) find the sum of the first 10 terms of the following series

    a)3,8,13,18
    b)1,3,9,27

    3) the first term of an arithmetic series is 1. the common difference is 6 find the 10th term of the series, the sum of the first N terms is 7400 find N


    if anyone can help me with this ill be greatly appreciated and i'll owe you one big time ;)
    If you gave me the correct formulas then... (which you didn't, the sum of n terms for geometric series is a(1-r^n)/1-r if I remember correctly - idk about the others though so I'm trusting you)

    1.

    a) 23
    b) 31
    c) 156250
    d) 4374

    2.

    a) 255
    b) 29524


    Sorry had the tab open for ages and forgot about it :p

    edit: o didn't see other guys post or a Q3...

    We seem to have gotten something different for 2a though. I think I went wrong somewhere :p

    edit2:

    No, I was right

    Quote:
     
    a)3,8,13,18 arithmetic 10/2(3+(10-1)*5) =240


    I got 5(6+9*5)=255. You need to double a from 3 to 6 according to the formula he gave
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    TheTankProd
    Zapdos
    tbh matt, wen i made this post the first two people i was expecting to solve this was either you or damo, (that's a compliment) thanks for your help owe you one ;)
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    Zach
    Member Avatar
    M.O.B Klick TO
    Nico
    Jun 11 2012, 09:38 PM
    so playing runescape is now proven to be beneficial to education!
    Ricki helped me with my hw a few times :P
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    Bashing
    Member Avatar
    IRON MAN
    Beat me to it, niggers
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    hai_im_Dave
    Rhydon
    Posted Image
    Edited by hai_im_Dave, Jun 24 2012, 10:55 PM.
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    Damian
    Member Avatar
    Psychic
    TheTankProd
    Jun 11 2012, 11:13 PM
    tbh matt, wen i made this post the first two people i was expecting to solve this was either you or damo, (that's a compliment) thanks for your help owe you one ;)
    I saw bill and matt posting when I opened it so I let them spend time on it rather than do it myself ;D

    and lmfao dave nice find :p
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