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Show me how this equation is valid

  1. May 28, 2014 #1
    Please, hurry. It's driving me nuts
     

    Attached Files:

  2. jcsd
  3. May 28, 2014 #2
    I suppose ##f \geq 0##? If so, ##y\geq x \implies yf(y) \geq xf(y)##.
     
  4. May 28, 2014 #3
    Seconded. Note that y takes on every value >= x, so you have basically replaced the constant x with the increasing function y in the integral.
     
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