已到x十Y二1,xY=5分之一,求x的平方Y十xY的平方-搜答案-智慧作业帮

∵x分之1-y分之1=5∴(x分之1-y分之1)^2=25∴(x^2)分之1+(y^2)分之1+2*(x分之1)*(y分之1)=25∴(x^2)分之1+(y^2)分之1-2=25∴(x^2)分之1+(

(3x-5xy+3y)/(x+xy+y)分式上下同除xy,得,(3/y-5+3/x)/(1/y+1+1/x)=1/3再问：太给力了，你的回答完美解决了我的问题！

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

x-3xy-Y分之3x+5xy-3y==(3x+5xy-3y)/(x-3xy-Y)=(5+3*(1/y-1/x))/(-3+(1/y-1/x)).分子分母同时除以xy=(5-21)/(-3-7).将x

14

原式=3分之1*(x²-3xy-10y²)=3分之1*(x-5y)(x+2y)

1/2x²+xy+1/2y²=1/2(x²+2xy+y²)=1/2(x+y)²=1/2

|x-1|+|y+3|=0|x-1|≥0|y+3|≥0所以x-1=0,y+3=0x=1,y=-3原式=1/1*-3+1/3*-1+1/1*5+1/3*7+1/5*9+.+1/(2n-1)(2n+3)=

∵x分之1-y分之1=3∴y分之1-x分之1=-3(x-2xy-y)分之(3x-5xy-3y)分子分母同时除以xy得=(y分之1-2-x分之1)分之(x分之3-5-y分之3)=[(y分之1-x分之1)

由已知得：xy=-1,1/x-1/y=(y-x)/(xy)=5那么：y-x=5xy=-5所以：(y-x)²=25即：y²-2xy+x²=25得：y²+x

1/xy+1/(x+1)(y+1)+1/(x+2)(y+2)+…+1/(x+2010)(y+2010)=1/（1*2）+1/（2*3）+1/（3*4）+.+1/（2011*2012)=1/1-1/2+

1/x+1/y=(x+y)/xy=2x+y=2xy(3x+7xy+3y)/(2x-5xy+2y)=[3(x+y)+7xy]/[2(x+y)-5xy]=(6xy+7xy)/(4xy-5xy)=13xy/

因为(x+1/y)(y+1/x)=xy+1+1+1/xy=18+2=20所以y+1/x=20/5=4再问：哦再问：我没想到，，，，

1/x+1/y=（x+y)/xy=5x+y=5xy所以原式=[2(x+y)-3xy]÷[(x+y)+2xy]=[2(5xy)-3xy]÷[(5xy)+2xy]=7xy÷7xy=1再问：1/x+1/y=

1/x+1/y=(x+y)/xy=5==>x+y=5xy所以2x-3xy+2y=2(x+y)-3xy=2*5xy-3xy=7xyx+2xy+y=5xy+2xy=7xy所以2x-3xy+2y除以x+2x

x^2y+xy^2=xy(x+y)=1/5(x^2+1)(y^2+1)=(xy)^2+x^2+y^2+1=(xy)^2+(x+y)^2-2xy+1=1/25+1-2/5+1=41/25再问：（X的平方

X=1,Y=2,XY=2;

x(x十y)(x一y)一x(x十y)²=x(x十y)[(x一y)一(x十y)]=x(x十y)*（-2y）=-2xy（x+y）=-2*6*5=-60

选择题最好的方法：设X=2,Y=1或X=-2,Y＝-1,则1/X+1/Y＝1/2+1＝1.5或1/X+1/Y＝－（1/2+1）＝-1.5