Answers

2015-08-26T11:13:43+08:00
1/x - 1/y = -x +y over xy 
1/x^2+1/y^2 = x^2 + y^2 over x^2 y^

= -x^2y+xy^2 over x^2+y^2

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I don't think that's the answer
I don't think too. I need to delete it.
Its correct, I think..
2015-08-26T17:15:41+08:00
  ( 1/x - 1/y )  / ( 1/x² + 1/y² )
=( y-x/xy ) / ( x²+y²/x²y² )
=( y-x/xy ) · ( x²y²/x²+y² )
=( x²y³ - x³y² ) / ( x³y + xy³)
=( xy² - x²y ) / ( x² + y² )
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