x加y=5,xy=3,则x的平方加y的平方=

1/x-1/y=(y-x)/xy=-3y=x=-3xyx-y=3xy所以原式=[5(x-y)+xy]/(x-y)-xy]=[5(3xy)+xy]/[(3xy)-xy]=16xy/2xy=8

你看看我的题意理解的对不对,不对的话,你再追问就好了.朋友想念你很高兴为您解答!请放心使用,有问题的话请追问采纳后你将获得5财富值.你的采纳将是我继续努力帮助他人的最强动力!

x+y=5(x+y)²=25x²+2xy+y²=25x²+y²=25-2xyx²+y²=25-12x²+y²=

x-y=2xy3x-5xy-3y/x+xy-y=[3(x-y)-5xy]/[(x-y)+xy]=(6xy-5xy)/(2xy+xy)=1/31/x+1/y=4y+x=4xyx-5xy+y/2x+xy+

2x^2+9xy+5y^2=0假设y不等于0,将方程两端同除以y^2,得：2（x/y）^2+9x/y+5=0解得：x/y=（-9+根号下41）/4或者（-9-根号下41）/4如果y=0,则y分之x不成

(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/x+y=3xy=3(x+y)3x-5xy+3y/-x+3xy-y=(3x+3y)-5*3(x+y)/[-x-y+3*3(x+y)]=-12(x+y)/8(x+y)=-3/2望采纳,谢谢!

学了一元二次方程了吗?

x+y=-3x=-y-3xy=2(-y-3)y=2-y²-3y-2=0y²+3y+2=0（y+1）（y+2）=0y1=-1y2=-2一、当y1=-1时,x1=-2,根号y分之x加根

1/x-1/y=3(y-x)/xy=3y-x=3xyx-y=-3xy(5x+xy-5y)/(x-xy-y)=[5(x-y)+xy][(x-y)-xy]=(-15xy+xy)/(-3xy-xy)=-14

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

x²/2+xy+y²/2=(x²+2xy+y²)/2=(x+y)²/2=3²/2=9/2

因为xy/（x+y）=1/2所以x+y=2xy原式=3（x+y)-5xy/(-x-y+3xy)=3*2xy-5xy/(-2xy+3xy)=xy/xy=1

x的平方+xy+y的平方=0x的平方+y的平方=-xyx/y+y/x=-1如追加其它问题,采纳本题后点击想我求助,

xy/x+y=3xy=3（x+y）3x-5xy+3y/-x+3xy-y=3x-15（x+y）+3y/-x+9（x+y）-y=-12(x+y)/8（x+y）=-3/2

2x²-3xy+y²=0（2x-y）（x-y）=0所以x=y或者2x=y当x=y时,x/y+y/x=1+1=2当2x=y时,x/y+y/x=1/2+2=5/2

3(x^2-xy)-xy+y^2=3(x^2-xy)-(xy-y^2)=3*5-(-3)=15+3=18

xy/(x+y)=2xy=2(x+y)(3x-5xy+3y)/(-x+2xy-y)=[3(x+y)-5xy]/[2xy-(x+y)]=[3(x+y)-10(x+y)]/[4(x+y)-(x+y)]=-

x+y=5xy（2x-3xy+2y)/(x+2xy+y）=[2（x+y）-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问：若x＋1/x＝3,求(x

因为,x-y=3xy所以：-3x+6xy+3y/[(7x-5y)-9xy-(3x-y)]=[-3(x-y)+6xy]/[(7x-5y)-9xy-(3x-y)]=[-3*3xy+6xy]/[7x-5y-