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Math questionpossible k values?

  1. Sep 8, 2010 #1
    If k is an integer and the number 1 + k, 1 + 2k and 1 + 8k are 3, 5 and 7, respectively, then the smallest possible value of k lies in the interval:
    A) 0 to 20
    B) 21 to 40
    C) 41 to 60
    D) 61 to 80
    E) None

    i reallyy don't know how to do this question..school just started 2 days ago and this is just a warm up question my teacher gave us to do..i honestly don't know where to start..if you don't want to give me the full answer, at least start me off..im pretty sure i'll be able to do it :)
     
  2. jcsd
  3. Sep 8, 2010 #2
    ok so i tried something..i think the answer is E but the way i did it seems too easy lol..he said it was a challenging question but none is an option too, right?!

    1 + k = 3 --> k=2
    1+ 2k= 5 --> k=2
    1 +8k= 7 --> k=6/8

    so would it be none??..i hate questions like these..i have a feeling its supposed to be a lot harder :s
     
  4. Sep 9, 2010 #3

    Mark44

    Staff: Mentor

    Your work looks fine. If 1 + k = 3, then clearly k = 2. This also works in the second equation, but not the third, so there is no value of k that satisfies all three equations.

    Sometimes the hardest part of a problem is coming up with a strategy. Once you have a good strategy, the actual work involved can be easy.
     
  5. Sep 9, 2010 #4

    hunt_mat

    User Avatar
    Homework Helper

    Could something mod 10 be going on?
     
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