x-y分之x² y² y-x分之2xy

原式=[(x+2y)/(x+y)][xy/(x+2y)]÷[(x+y)/xy]=[xy/(x+y)]×xy/(x+y)=x²y²/(x+y)²

2x-y分之x+y=2,则2x-y=2(x+y)4x-2y分之x+y-4x+4y分之2x-y=2(2x-y)分之x+y-4(x+y)分之2x-y=4(x+y)分之x+y-4(x+y)分之2(x+y)=

（x的平方-y的平方)分之2xy+(x+y)分之x-(y-x)分之y=（x的平方-y的平方)分之2xy+(x+y)分之x+(x-y)分之y=(x²-y²)分之[2xy+x(x-y)

后面那个x-y分之2{x＋y}-3{x＋y}分之x-y是怎么回事,能清楚一点吗前一个化简得x=-3y;后一个得(-4y/-4y)-4y/6y=1-2/3=1/3

2/3

（x分之x-y）-（y分之x+y）+（2xy分之x的平方-y的平方）=1-y/x-1-x/y+(x^2-y^2)/2xy=-2(y^2+x^2)/2xy+(x^2-y^2)/2xy=-(x^2+3y^

1x^2y分之x^4=x²/y2ab分之ab-b^2(b不等于0）=1-b/a36abc^2分之36ab^3c=6b²/c4a^2-b^2分之（a+b)^3=（a+b）²

原式=x/(x-y)+y³/x(x-y)²÷[-y(x+y)/(x+y)(x-y)]=x/(x-y)-y³/x(x-y)²×(x-y)/y=x/(x-y)-y&

因为x+y分之2x-y=2又因为x+y分之4x-2y是它的2倍所以x+y分之4x-2y就=4因为x+y分之2x-y=2倒过来2x-y分之x+y就为1/2又2x-y分之4x+4y是2x-y分之x+y的4

x+y分之x-y=2求x+y分之3x-3y减x-y分之2(x+y)的值x+y分之x-y=2x-y=2(x+y)(x+y)分之(3x-3y)-(x-y)分之2(x+y)的值x+y分之3x-3y=(x+y

x+y分之x-y=2x-y=2(x+y)求x+y分之3x-3y=(x+y)分之3(x-y)=(x+y)分之6(x-y)=6-x-y分之2(x+y)=-(x+y)分之2(x+y)=-2

x+2y+4y^2/(x-2y)-4x^2y/(x-4y^2)=x+2y+4y^2/(x-2y)-4x^2y/[(x+2y)(x-2y)]通分,分母为[(x+2y)(x-2y)]=(x+2y)(x+2

(y+z-2z)这步有错吧

原式=1/2x-1/(x+y)[(x+y)/2x-(x+y)]=1/2x-(1/2x-1)=1/2x-1/2x+1=1

原式=[(x+2y)/(x+y)]×[xy/(x+2y)]÷[(x+y)/xy]=[(x+2y)/(x+y)]×[xy/(x+2y)]×[xy/(x+y)]=x²y²(x+2y)/

2x/(2x-y)+y/(y-2x)=2x/(2x-y)-y/(2x-y)=(2x-y)/(2x-y)=1

x-4y分之3x+4y-x分之x+y-x-4y分之7y=3x/(x-4y)-(x+y)/(x-4y)-7y/(x-4y)=(3x-x-y-7y)/(x-4y)=(2x-8y)/(x-4y)=2

是这样的形式吗?[x/（x+y）+2y/（x+y）]×[xy/（x+y）]÷（1/x+1/y）一:原式=（x+2y）/（x+y）×[xy/（x+2y）]÷[（x+y）/xy]=x²y&sup

三分之X-Y+四分之X+Y=-2(1)六分之X-Y-八分之X+Y=3(2)(1)*1/2得六分之X-Y+八分之X+Y=-1(3)(2)+(3)得三分之X-Y=2,X-Y=6设Y=X-6(4)代入（1）

（x^2-y^2）÷（x分之x-y+y^2分之x^2-y^2-x-y分之x+y）=（x^2-y^2）÷（1-y+x^2/y^2-y^2-x-x/y+y）=（x^2-y^2）÷（1-y+y+x^2/y^