(x y) (2x 1乘2分之y)

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

(xy-x的平方）除以xy分之x的平方-2xy+y的平方乘x的平方分之x-y=x(y-x)*xy/(x-y)²*（x-y）/x²=-y再问：不好意思，打错了(xy-y的平方）除以x

(xy-x²)÷(x²-2xy+y²)/(x-y)×(x-y)/x²=-x(x-y)÷(x-y)²/x²=-x(x-y)×x²/(

∵x^2+y^2-2x+4y+5=0配方：∴(x-1)^2+(y+2)^2=0那么x-1=0且y+2=0所以x=1,y=-2∴(x^4-y^4)/(2x^2+xy-y^2)*（2x-y)/(xy-y^

(1)（xy-x²)除以xy分之x²+y²-2xy乘x²分之x-y=x(y-x)×xy/(x-y)²×(x-y)/x²=-y(2)先化简：（

-4分之3(-2x的平方y)的平方乘(-3分之1xy)-(-xy)的3次方×(-x的平方)=x^5y^3-x^5y^3=0

(3y分之2x²）²乘4x分之3y+2y²分之x²除以xy分之3=4x^4/9y^2*3y/4x+x^2/2y^2*xy/3=x^3/3y+x^3/(6y)=(

(xy-x²)÷(x²-2xy+y²)/(x-y)×(x-y)/x²=-x(x-y)÷(x-y)²/x²=-x(x-y)×x²/(

：（xy-x²）÷xy分之x²-2xy+y²乘x²分之x-y=-x(x-y)×xy/(x-y)²×(x-y)/x²=-y∴结果与x的值没有关

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)/

1.若x分之1-y分之1=2,则求x-xy-y分之3x+xy-3y=0的值.若x分之1-y分之1=2变形（y-x）/xy=2,(y-x)=2xy(3x+xy-3y)/(x-xy-y)=[3(x-y)+

带入x=3y,分母为9y^2-6y^2+y^2=4y^2.分子为7y*2y=14y^2.所以原式=7/2.

（xy-x²）乘（x-y）分之xy=-x(x-y)乘[(x-y)分之xy]=-x²y

X²+2xy+y²/xy乘x²-2xy+y²/xy+y²=(x+y)²/xy×(x-y)²/y(x+y)=(x+y)(x-y)&#

[(x^4-y^4)/(x^2-2xy+y^2)]*(y-x)/(x^2+y^2)=[(x-y)(x+y)(x^2+y^2)/(x-y)^2]*(y-x)/(x^2+y^2)=[(x^2+y^2)(x

7分之1xy的2次方乘14(xy)的2次方乘4分之1x的5次方=1/7xy²*14(xy)^2*1/4x^5=2x^8*y^4=2*(4)^8*(-1/8)^4=2*2^16*2^(-12)

x2/x1²+x1/x2²=(x1³+x2³)/x1²x2²=(x1+x2)(x1²-x1x2+x2²)/(x1x2)&

原式=4(x-y)²/2(x+y)(x-y)*(x+y)/xy(x-y)=2(x-y)/(x+y)*(x+y)/xy(x-y)=2/xy=2/(2*3)=1/3再问：先化简，再求值额。。。

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

(-2x2次方y)乘(-三分之二xy)乘(-8xy)=-32/3X^(2+1+1)Y^(1+1+1)=-32/3*X^4Y^3