(x y) 2(x-y) 代入法计算-搜答案-搜搜考试网

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

(x+2y-3xy)-(-2x-y+xy)=x+2y-3xy+2x+y-xy=3(X+Y)-4xyx+y=二分之一,xy=-二分之一带入得：原式=3*1/2-4*(-1/2)=7/2

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

y=3(x-y),x=2(x-y)x=0y=0再问：请问，怎样解=0，要过程，谢谢再答：y=3(x-y)=3x-3y4y=3xy=3x/4x=2(x-y)=2x-2y=2x-3x/2=x/2x-x/2

(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

2x+3y-2=0y=(2-2x)/32x-3y+5+2y=9为2x+5-(2-2x)/3=9x=1.75

（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

2x+3y=12(1)3x-4y=17(2)由(1)得y=(12-2x)/3代入(2)4x-(48-8x)/3=1712x-48+8x=5120x=99所以x=99/20y=(12-2x)/3=7/1

2y=5x-3代入得3x-2(5x-3)=-1x=1y=1a=1/3b-12b-5/3b+5=1b=-12a=-52、把x=1y=3和x=2y=3分别代入方程3=k+b3=2k+bk=0b=33、把x

y=x-3代入方程2y+3x-3y=112(x-3)+3x-3(x-3)=112x-6+3x-3x+9=112x=8x=4y=x-3=1

(x-2y)²+(x+2y)(x-2y)-(x-3y)(x-y)=x²-4xy+4y²+x²-4y²-x²+4xy-3y²=x&s

x-y/xy-y^2计算

解(x-y)/(xy-y²)=(x-y)/y(x-y)=1/y