Simple math question

Discussion in 'Math' started by tadm123, Feb 7, 2014.

  1. tadm123

    Thread Starter Member

    Nov 20, 2013
    43
    0
    In an engineering lecture I'm stuck in this part, this is one of those problems where you know it is pretty dumb but can't get out of it. Here's the link:

    http://s18.postimg.org/ytzfn0wnt/equation.jpg

    Can anyone explain me how they got a simplified Re/re from there?

    I divided both of the numbers in that equation and got a (Re+re)/re.
    How did they get rid of that "re" in the numerator and simplify it in that form?

    Thanks in advance
     
    Last edited: Feb 7, 2014
  2. MrChips

    Moderator

    Oct 2, 2009
    12,418
    3,355
    (Re + re)/re = Re/re + 1

    But I get

    Re/re + 1 >= 2.3716

    Re/re >= 1.3716
     
    tadm123 likes this.
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    \frac{Re+re}{re}\geq\frac{27*13}{10*14.8}
    \frac{Re}{re}+\frac{re}{re}\geq\frac{351}{148}
    \frac{Re}{re}+1\geq2.372
    \frac{Re}{re}\geq2.372-1
    \frac{Re}{re}\geq1.372
     
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  4. tadm123

    Thread Starter Member

    Nov 20, 2013
    43
    0
    I feel so stupid, of course you distribute them.

    Yeah, I also get 1.372. They must had simplify the 14.8/13 which gets you 1.1 and then use that to divide it.

    Anyways, thanks for the replies guys.
     
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