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X^2 - y^2 = x - y , ?

  1. Oct 12, 2003 #1
    x^2 - y^2 = x - y , ?????

    if y not equal x .

    what is y and x when

    x^2 - y^2 = x - y

    ---------------------------
     
  2. jcsd
  3. Oct 12, 2003 #2
    Only solution I can think of is when x and y is equal to one.
    You get:

    x = 1; y = 1;

    (1)^2 - (1)^2 = (1) - (1)
    ==> 0 = 0
     
  4. Oct 12, 2003 #3
    he asked for solution in which x doesnt equal y.

    now i know it's simple but the question seems to be simple
    x^2-y^2=x-y
    (x-y)*(x+y)=x-y /x-y
    x+y=1
    now for positive integers it could only be x=0 y=1 or the opposite, the other solutions are negative integers and positive ones.

    btw, can someone explain how is this a question about calculus?
     
  5. Oct 12, 2003 #4

    mathman

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    Unless there is a further restriction on x and y (the original question didn't include any), then x+y=1, for any x, will do.
     
  6. Oct 13, 2003 #5
    Gah, don't be tired and browes PF at the same time :P
     
  7. Oct 21, 2003 #6
    use implicit differentiation and find the derivative
     
  8. Oct 21, 2003 #7

    mathman

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    What has this got to do with it???????
     
  9. Oct 27, 2003 #8
    I also wonder the same , and how is that will be useful ?
     
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