求适合3分之2x y=5分之x 3y=1的x和y的值

由xy/（x+y）=2,∴xy=2（x+y）∵（-x+2xy-y）/（3x-5xy+3y）=（-x-y+4x+4y）/3x+3y-10x-10y）=（3x+3y）/（-7x-7y）=-3/7.

1、答案：负七分之五解题：xy=2x+2y代入原式,整理合并同类项即可得出2、如果只考虑在同一平面内,有三条线.如图

5分之2+4分之3X3分之2-20分之13=(1/4)＝2/5+1/2-13/20＝2/5-3/20＝5/20=1/44分之3X15分之4+5分之2/5分之4=(7/10)=1/5+1/2=7/101

解1/x+1/y=5即(y+x)/xy=5∴y+x=5xy∴(2x+3xy+2y)/(x-2xy+y)=[2(x+y)+3xy]/[(x+y)-2xy]=[2×5xy+3xy]/(5xy-2xy)=(

1x2分之1-2x3分之1-3x4分之1-...-9x10分之1=1/1-1/2+1/2-1/3+1/3-1/4+1/4-.-1/9+1/9-1/10=1-1/10=9/101x3分之2+3x5分之2

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

∵(x+y)分之xy=3∴xy=3(x+y)∴(-2x+3xy-2y)分之(3x-5xy+3y)=[-2(x+y)+9(x+y)]分之[3(x+y)-15(x+y)]=[7(x+y)]分之[-12(x

5/1215/87/607/521/281/9

3xy-[2xy-2(xy-2分之3xy)+xy]+3xy=6xy-[2xy-2xy+3xy+xy)=6xy-4xy=2xy=2×3×3分之1=2

1/x+1/y=(x+y)/(xy)=5x+y=5xy(2x-3xy+2y)/(x+2xy+y)=(2*5xy-3xy)/(5xy+2xy)=(10-3)/(5+2)=1

因为X+Y分之XY=2,所以XY=2(X+Y)代入后面的分子式得：13（X+Y)/5(X+Y)=13/5

x+y分之xy=2,则xy/(x+y)=2xy=2x+2y(-x+3xy-y)分之(3x-5xy+3y)=(3x-5xy+3y)/(-x+3xy-y)=[3x-5(2x+2y)+3y)/[-x+3(2

(x分之1)+(y分之1)=5（x+y)/xy=5x+y=5xy代入（x+2xy+y)分之(2x-3xy+2y)=7xy分之7xy=1

因1/x+1/y=5(x+2xy+y)/(2x-3xy+2y)上下同乘以1/(xy)得[1/y+2+1/x]/[2/y-3+2/x]整理得[(1/x+1/y)+2]/[2(1/x+1/y)-3]将已知

(y-x)/xy=3y/xy-x/xy=3所以1/x-1/y=3(3x-5xy-3y)/(x-2xy-y)分子分母同时除以xy原式=(3/y-5-3/x)/(1/y-2-1/x)=[3(1/y-1/x

1/x-1/y=(y-x)/xy=2y-x=2xy(3x-5xy-3y)/(-x+3xy+y)={3(x-y)-5xy}/(y-x+3xy)={(-3)*2xy-5xy}/5xy=-11/5

x+y分之xy=2,则xy/(x+y)=2xy=2x+2y(-x+3xy-y)分之(3x-5xy+3y)=(3x-5xy+3y)/(-x+3xy-y)=[3x-5(2x+2y)+3y)/[-x+3(2

1/x-1/y=3(y-x)/xy=3y-x=3xyx-y=-3xy所以原式=[5(x-y)+3xy]/[(x-y)-2xy]=(-15xy+3xy)/(-3xy-2xy)=(-12xy)/(-5xy

(3x+5xy-3y)/(x-xy-y)=(3x-3xy-3y+8xy)/(x-xy-y)=3+8xy/(x-xy-y)=3+8/(1/y-1-1/x)=3+8/(-3)=1/3