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Math Help - Not sure of answers

  1. #1
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    Not sure of answers





    1) Find a formula for the nth term of the sequence: 0,-1,0,1,0,-1,0,1,0,-1,0,1 -------- I got an= sin (nn)

    2) Find limit of sequence if it converges:
    an = 3-8n+4n^4/(3n^4+9n^3-2) -------- I got 4/3

    3) Find limit of sequence if it converges; an = (3/n) subscript(3/n) --- I got 0.

    4) Find limit of sequence if it converges; an= 5+ (-1)^n / 5 ---- I got 1

    5) Determine if the sequnce is decreasing/non-decreasing/bound/unbounde… :
    an = (4n+1)/(n+1) ----- I got nondecreasing, bounded


    If the answers aren't right, could someone explain/show what the correct answer is?
    Last edited by MathFeed; November 8th 2009 at 03:41 PM.
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  2. #2
    No one in Particular VonNemo19's Avatar
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    Quote Originally Posted by MathFeed View Post


    1) Write the first 4 elements of the sequence: (n+1)/(3n-1)
    I got -1,1,3/5,1/2 not quite

    2) Find a formula for the nth term of the sequence: 0,-1,0,1,0,-1,0,1,0,-1,0,1 -------- I got an= sin (nn) If n starts at 1, then -\sin[(n-1)\frac{\pi}{2}]

    3) Find limit of sequence if it converges:
    an = 3-8n+4n^4/(3n^4+9n^3-2) -------- I got 4/3 good

    4) Find limit of sequence if it converges; an = (3/n) subscript(3/n) --- I got 0.
    I dont understand your language
    5) Find limit of sequence if it converges; an= 5+ (-1)^n / 5 ---- I got 1 Diverges

    6) Determine if the sequnce is decreasing/non-decreasing/bound/unbounde… :
    an = (4n+1)/(n+1) ----- I got nondecreasing, bounded


    If the answers aren't right, could someone explain/show what the correct answer is?
    ...
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  3. #3
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    Could you explain 5 & 6?
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  4. #4
    No one in Particular VonNemo19's Avatar
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    Quote Originally Posted by MathFeed View Post
    Could you explain 5 & 6?
    Sure.

    5. Assume n even, then take the limit. Assume n odd, then take the limit. You'll see that one goes to \infty, while the other goes to -\infty

    6. is correct. if you take the derivative, note that the sequence is positive for all x>1. Also, the limit of the sequence is 4.
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