X-3Y=0,求2X Y除以X的平方-2XY Y的平方乘以X-Y的值

由X+Y=3XY可得X+Y-XY=2XY,用X+Y-XY替换分母中的2XY,所以(2X+2Y-XY)/(X+Y+2XY)=(2X+2Y-XY)/(2X+2Y-XY)=1

x-3y=0x=3y(2x+y)/(x^2-2xy+y^2)÷1/(x-y)=(2x+y)/(x-y)^2÷1/(x-y)=(2x+y)/(x-y)^2*(x-y)=(2x+y)/(x-y)=(2*3

3x^2+xy-2y^2=(3x-2y)(x+y)=0x=-2y/3,或x=-y但由于你要求的式子中分母里有X平方-Y平方x=-y舍去其他就代入吧

把3x＋2y转化成分式.同时÷xy再算就行了

式子是这样么(2x+y)/(x^2-2xy+y^2）=(2x+y)/(x-y)^2x-3y=0x=3y代入原式(2*3y+y)/(3y-y)^2=7/4yy不能等于0

2x²-3xy-2y²=0(x-2y)(2x+y)=0x1=2y1,x2=-y2/2又∵x＞0,y＞0∴x=2y∴(x+y)/(x-y)=(2y+y)/(2y-y)=3

^2代表平方,/代表分数线和除号由题意得设x=3k,y=2k（k不等于0）代入原式=(9k^2+18k^2)/(6k^2+8k^2)=27k^2/14k^2=27/14所以原式的值为14分之27.

此题应该抄错了,应该是遗漏了一个x,∵xy/(x+y)=2∴1/x+1/y=1/2(3x-5xy+3y)/(-x+3xy-y)=(3x-5xy+3y)/(-x+3xy-y)[分子分母同除以xy,得]=

由于xy除以x+y=2故xy=2（x+y）将这代入8x-5xy+8y除以-x+3xy-y化简得其中的（x+y）会相互约去故8x-5xy+8y除以-x+3xy-y=-2/5希望这个能帮到你over~

x²+3xy-4y²=0(x-y)(x+4y)=0x=y或者x=-4y所以（x-2y）÷（x+2y）当x=y的时候原式子=（x-2x）÷（x+2x）=-1/3当x=-4y的时候（-

x的平方+3xy+2y的平方除以x的平方y+2xy的平方=(x+2y)(x+y)/xy(x+2y)=12/9=4/3再问：那个再问一下不改变分式的值使分式的分子分母首项系数都是正数-(负7xy/负8z

y－x－2xy＝0(3x＋xy－3y)/(y－xy－x)＝(3x＋6xy－5xy－3y)/(y＋xy－2xy－x)＝[-3(y－x－2xy)－5xy]/(y－x－2xy)＋xy＝(0－5xy)/(0＋

(x-2y)(3+x)=0x-2y=0x=2yx+3=0x=-3y=-3/2(3x^2+3xy)/(3xy-x+6y)=(27+27/2)/(27/2+3-9)=-81/135=-3/5

原式=[4(x+y)-2xy]分之[(x+y)+xy]=[4(3xy)-2xy]分之[(3xy)+xy]=10xy分之2xy=5分之1

1、x-2√xy-3y=（√x-3√y)(√x+√y)=0解得√x=3√y或者√x=-√y（舍去）也就是x=9y2x+y+√xy除以y-x-√xy=(2*9y+y+3√y*√y)/(y-9y-3√y*

2X^2+3XY+Y^2=0,（2X+Y）（X+Y）=0所以X/Y=-1/2或x/y=-1所以x/y+y/x=-1/2-2=-5/2或x/y+y/x=-1-1=-2

x-2√xy-15y=0(√x-5√y)(√x+3√y)=0x>0,y>0所以后一个括号大于0所以√x-5√y=0√x=5√yx=25y√xy=5y所以原式=(50y+5y+3y)÷(25y+5y-y

由x-√xy-2y=0可知,（√x+√y）（√x-2√y）=0解得√x=2√y,即x=4y则（2x-√xy）/(y+2√xy)=(2x-2y)/(y+4y)=6/5

(x-y)(x-3y)=0x=y或x=3yx/y+y/x=1+1=2或3+1/3=10/3

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