1.( x-y)/(2x+2y)与xy/(x+y)^2分母是2(x+y)和(x+y)^2所以最简公分母是2(x+y)^2所以( x-y)/(2x+2y)=(x+y)(x-y)/2(x+y)^2xy/(x+y)^2=2xy/2(x+y)^22.2mn/(4m^2-9)与2m-3/(2m+3) 分母是(2m+3)(2m-3)和2m+3所以最简公分母...