即xy=2²-(√3)
=4-3=1
原式=[(x+y)²-(x-y)²]/(x+y)(x-y)*[-(x²-y²)/x²y²]
=(x²+2xy+y²-x²+2xy-y²)/(x+y)(x-y)*[-(x²-y²)/x²y²]
=-4xy/(x²-y²)*(x²-y²)/x²y²
=-4/xy
=-4/1
=-4 即xy=2²-(√3)
=4-3=1
原式=[(x+y)²-(x-y)²]/(x+y)(x-y)*[-(x²-y²)/x²y²]
=(x²+2xy+y²-x²+2xy-y²)/(x+y)(x-y)*[-(x²-y²)/x²y²]
=-4xy/(x²-y²)*(x²-y²)/x²y²
=-4/xy
=-4/1
=-4