[2/xy/(1/x+1/y)²+(x²+y²)/(x²+2xy+y²)]*2x/(x-y)
=[2/xy/(x+y)²/x²y²+(x²+y²)/(x+y)²]*2x/(x-y)
=[2xy/(x+y)²+(x²+y²)/(x+y)²]*2x/(x-y)
=[(2xy+x²+y²)/(x+y)²]*2x/(x-y)
=(x+y)²/(x+y)²*2x/(x-y)
=2x/(x-y)