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Conditions for which inequalitys is true

  1. Mar 18, 2009 #1
    A:
    1-mt<w^2(m+t)

    B:
    -(1+mt)<(w^2 )t(m-t)


    i have 4 cases
    for each case they said that needs to be a condition for which this case would be true
    1: m>t and mt<1
    so they say that i have to demand
    w^2>(1-mt)/(m+t) which is inequality A

    2: m<t and mt<1
    they say that i have to demand
    inequalitys A and B

    why ??
     
  2. jcsd
  3. Mar 18, 2009 #2

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    If m< t, m- t is negative, if m> t, m- t is positive, if mt< 1, 1-mt is positive and w^2 is always positive.
     
  4. Mar 18, 2009 #3
    so why in case two they demand both ??
    it seems like the left side is true always
    it cannot be negative?
     
  5. Mar 18, 2009 #4
    why in the 1st case we only pick only one innequality
    ??
     
  6. Mar 18, 2009 #5
    even if i substitute what you say regarding the positive and negative
    i get
    positive>positive

    so??
     
  7. Mar 18, 2009 #6
    wwoowww thanks i understood that stuff
    :)
     
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