已知一个分式*y分之2x的3次方所得的结果是-2分之3x的平方,那么这个分式是-搜答案-智慧作业帮

设k.x=2k,y=3k原式=-12/5

原式＝(x^2-2x+1)+(y^2-4y+4)=(x-1)^2+(y-2)^2=0,所以x=1,y=2,代入问题得结果为3/2

由1/x-1/y=3得(y-x)/xy=3题中的式子分子分母同时除以xy得(2/y+3-2/x)/(1/y-2-1/x),通分得【2(x-y)/xy+3】/【(x-y)/xy-2】代入得3/5

1/x--1/y=3,化简y--x=3xy(2x-3xy-2y)/(x-2xy-y)=[-2(y-x)-3xy]/(x-y-2xy)=-9xy/-5xy=9/5

1/x-1/y=2所以得：x-y=-2xy；代入下式(x-2xy-y)/(2x-3xy-2y)=(-2xy-2xy)/(-4xy-3xy)=4/7

x²+3分之x-2y的值为0∵x²+3>0∴x-2y=0∴x=2yx²-y²分之x²-3xy-4y²=(x-4y)(x+y)/(x+y)(x

2x=-yy=-2xxy/(x^2-y^2)=x*(-2x)/[x^2-(-2x)^2]=-2x^2/[x^2+4x^2]=-2x^2/5x^2=-2/5

∵x/y=2/3∴设x=2t,y=3t∴(x²+3xy)/(x²+xy-6y²)=(4t²+3×2t×3t)/(4t²+2t×3t-6×9t²

三分之X=四分之Y=五分之Zx：y：z=3:4:5设x=3ay=4az=5a(x+y)/(x-2y+3z)=(3a+4a)/(3a-8a+15a)=7a/10a=7/10

假设x分之3=y分之4=z分之5=1,则x=3,y=4,z=53x-2y+z分之x+y+z=(3x3-2x4+5)分之（3+4+5）=6分之12=2http://zhidao.baidu.com/li

8,应该是的

y-x=3xyx-y=-3xyx-2xy-y=-5xy2x+3xy-2y=2(x+y)+3xy=-6xy+3xy=-3xy分式x-2xy-y分之2x+3xy-2y=5/3

∵x-3y=0∴x=3y(x²+y²)分之(x²-3xy+y²)=[(3y)²+y²]分之[(3y)²-3(3y)y+y²

(2x^2+3xy-2y^2)/(x^2+3xy+2y^2)={(2x-y)(x+2y)}/{(x+y)(x+2y)}=(2x-y)/(x+y)=02x-y=0

1/x+1/y=5(x+y)/x*y=5x+y=5*x*yx+2xy+y=x+y+2xy=5xy+2xy=7xy2x-3xy+2y=10xy-3xy=7xy(2x-3xy+2y)/(x+2xy+y)=

y=4x带入3x-y=3x-4x=-xx+y=x+4x=5x(x+y)/(3x-y)=5x/(-x)=-5

3x+2y=0y=-1.5xx/y=x/-1.5x=-2/3y分之3x+3=3x/-1.5x+3=1

1、题目是不是：已知2x-3y=0?如果是的话,原式=[y(x+1)]/[x(x+1)]=y/x=2/32、不成立,因为等式左边是0的倒数,无意义3、(a+c)/c=a/c+1=2/3+1=5/3,所

(x+3y)/2x,换X为1/13*X,Y为1/13*Y,代入后值不变,利用分式的基本性质可得.

1.整理得到算式[2x-x+y]/[x^2-y^2]=[x+y]/[x+y][x-y]=1/[x-y]代入得到1/72.整理得到[1-3/(a+2)]/[(a^2-2a+1)/(a^2-4)]=[(a