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GRE Test Question

  1. Feb 10, 2009 #1
    1. The problem statement, all variables and given/known data

    Hi,
    I was doing some GRE practice tests and came across this question:

    for all number n, [tex]n^*[/tex]=32-n (apparently where the asterisk is an exponent)

    They then give me two values, which are [tex](n^*)^*[/tex] and n, and I am to say whether choice 1 is a greater value than choice 2, choice 2 is a greater value than choice 1, the two values are equal, or there is not enough info to determine. The answer key says they are equal. This means given the above equation, [tex](n^*)^*[/tex] = n

    I can't see how this is true... Anyone care to explain? Thanks
     
  2. jcsd
  3. Feb 10, 2009 #2

    cristo

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    Let [itex]n^*=32-n=m[/itex]. Then, [itex](n^*)^*=m^*[/itex]. Can you evaluate [itex]m^*[/itex]?
     
  4. Feb 10, 2009 #3
    I'm not sure. Is there some way you want me to rewrite this? [itex]m^*=(32-n)^*[/itex]
     
  5. Feb 10, 2009 #4

    cristo

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    Yes. The star is shorthand for the operation that "subtracts a given number from 32." In the case of [itex]m^*[/itex], the given number is 32-n. What is the result when you apply * to that?
     
  6. Feb 10, 2009 #5
    lol, that was easy. I had in my mind that * was some sort of exponential value, not a more general operator. Thanks
     
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