在计算(x y)(x‐2y)‐my(nx‐y)-搜答案-百度作业网

等于1/X*（X-Y）

y/(x²-xy)+2/(y-x)-x/(y²-xy)=[y²+2(-xy)+x²]/(x²y-xy²)=(x-y)²/[(x-y

这是一个初中竞赛题目与高中的主要运用公式x^3-y^3=(x-y)(x^2+xy+y^2)x^3+y^3=(x+y)(x^2-xy+y^2)其中(x-y)(x^2+xy+y^2)=x(x^2+xy+y

3xy[2xy-x(y-2)+x-1]=3xy(2xy-xy+2x+x-1)=3xy(xy+3x-1)=3x^2y^2+9x^2y-3xy

3xy[2xy-x（y-2）+x]＝3xy[2xy-xy+2x+x]=3xy(xy+3x)=3x²y²+9x²y

4xy-(x+y)^2/xy(x+y)(x-y)÷x^2+xy-2y^2/x^2y+2xy^2=(4xy-x²-2xy-y²)/[xy(x+y)(x-y)]÷[(x-y)(x+2y

①2m²-m(2m-5n)-n(5m-n)=2m²-2m²+5mn-5mn+n²=n².②(3x-y)²-(3x+y)²-2xy=

计算x²y³-2x(4xy³)

x²y³-2x(4xy³)=x²y³-8x²y³=-7x²y³

(X+Y)(X^2-XY+Y^2)=(x*x^2-x*xy+x*y^2)+(x^2y-xy^2+y^3)=x^3+y^3这个是立方和的公式,再给你一个x^3-y^3=(X-Y)(X^2+XY+Y^2)

这题少括号了吧.

(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3=-(x-y)^3[-(xy-5)/x^2(x-y)]/[(xy-5)/xy]=(x-y)^3(xy-5)xy/x^2(x-y)(x

【x²+xy/（x-y）】/【xy/（x-y）】=【x²（x-y）/（x-y）+xy/（x-y）】/【xy/（x-y）】={【x²（x-y）+xy】/（x-y）}/【xy

（xy-y^2)÷x-y/xy=y(x-y)×[xy/(x-y)]=xy²

[(x²+2xy+y²)/(xy-y²)][(x²-2xy+y²)/(xy+y²)]={(x+y)²/[y(x-y)]}{(x-y

这个,最后面那个减号前面是怎么回事?打括号没有?这个很重要!再问：x-y/x²是一个整体分数，3个分数，啊！！！再答：把前面分子分母同城xy然后两个合并就可以了啊！

（2xy/-mn²）÷8x²/y²×（-2m/y²）³=2xy/mn^2*y^2/8x^2*8m^3/y^6=2m^2/n^2xy^3

1+2+3+…+m=px^my*x^(m-1)*y^2*x^(m-2)*y^3…*xy^m【其中^代表乘方】=x^{m+(m-1)+(m-2)+(m-3)+.1}y^{1+2+3+...m}=x^py

(1)X+Y=M(2)2X-Y=6(1)+(2)3X=M+6X=(M+6)/3=M/3+2Y=2X-6=(2M-6)/3=2M/3-2XY是整数所以M是3的倍数XY

x-y/xy-y^2计算

解(x-y)/(xy-y²)=(x-y)/y(x-y)=1/y

3(1,4)和0(2,2)