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Need a strategy for inverting a function

  1. Sep 27, 2007 #1
    I can't solve for y from:

    x = - [tex]K_{1}[/tex]* y *[tex]\sqrt{K_{2}-y}[/tex]

    where K(1) and K(2) are constants.

    I am pretty sure as a younger man I was taught how to do this but I can't remember the strategies I can/should use. Any thougths would be very appreciated.
    Last edited: Sep 27, 2007
  2. jcsd
  3. Sep 27, 2007 #2
    Square both sides and you get a cubic in y, out of which the solution y=0 is evident, so you've only got a simple quadratic to solve.
  4. Sep 27, 2007 #3

    Shooting Star

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  5. Sep 27, 2007 #4
  6. Sep 27, 2007 #5
    Thanks, and genneth I'm not one to talk!

    Shooting Star, It looks from the page you sent that the general form is:

    y = 3f/[-e+(e3-27f2)1/3],
    y = 3f/[-e+(e3-27f2)1/3(-1+sqrt[-3])/2],
    y = 3f/[-e+(e3-27f2)1/3(-1-sqrt[-3])/2].

    so only the first of these avoids i, right?
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