一、x-y/x+2y除x²-y²/x²+4xy+4xy²-2其中x=2+√3,y=2√3原式=(x-y)/(X+2Y)×(X+2Y)²/［(X+Y)(X-Y)］-2=(X+2Y)/(X+Y)-2=(-X-3Y)/(X+Y)当X=2+√3,Y=2√3时,原式=(-2-7√3)/(2+3√3)=-(2+7√3)...