分式x y分之3x平方中的x.y值同时扩大到原来的3倍-搜答案-拍题作业网

2/xy=2(y-x)/xy(y-x)3y/(xy-x^2)=3y^2/xy(y-x)如果不懂,请追问,祝学习愉快!

2(x²+2xy)=2x(x+2y)3(x²+4xy+4y)²=3(x+2y)²∴最简公分母是6x(x+2y)²

x-3y=0且xy≠0,所以x=3y(x≠0,y≠0)带入分式,(9y-3y+y)/(9y+3y+y)=7/13

(x²-4y²)/(x²+4x+4)×（x+2)/(3x²+6xy)=[（x+2y）(x-2y)]/(x+2)²×(x+2)/[3x(x+2)]=（x

x-y=x/y两边同乘以y得xy-y^2=x移项xy-x=y^2即x(y-1)=y^2x=y^2/(y-1)

x/y=3=>x=3y原式=(9y²+2*3y*y-3y²)/(9y²-3y*y+y²)=12/7再问：能不能先化简，后代入？再答：可以是可以，x²+

x平方减y平方等于0,(x+y)(x-y)=0x+y=0或x-y=0当x+y=0,则x=-y3x平方减2xy加4y分之x平方减3xy加5y平方=(3y²+2y²+4y²)

1、1/x-1/y=3(y-x)/xy=3y-x=3xyx-y=-3xy原式=[3(x-y)+xy]/[(x-y)-xy]=[3(-3xy)+xy]/[(-3xy)-xy]=-8xy/(-4xy)=2

(4-x²)/(x²y-2xy)=-(x²-4)/(x²y-2xy)=-(x+2)(x-2)/xy(x-2)=-(x+2)/xy愿对你有所帮助!

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

(x+3y)/(x²+xy)+(y-x)/(xy+y²)=(x+3y)[x(x+y)]-(x-y)/[y(x+y)]=[(x+3y)y-x(x-y)]/[xy(x+y)]=(xy+

因为x=3y,所以原式=[（3y)²-3y·y+y²]分之[(3y)²+2·3y·y-3y²]=7y²分之12y²=7分之12

x²-3xy+2y²=(x-y)(x-2y)=0x-y≠0,所以x-2y=0x=2y原式=(4y-3y)/(2y-y)=y/y=1

2(x平方-6分之7y）平方分之（x-3分之2y)平方

什么之啊?是不是除以?直接令x=2,y=3,就可以求出来了,如果是选择题的话,就直接可以这样做,要是计算题,可以令x=2a.或者别的,都可以

方法一：取特殊值x=1,y=2,代入即可.方法二：由y/x=2,得y=2x,代入要求的式子也行,但是注意运算要小心点.

(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

原式为2x^2/(x+y)xy都扩大3倍后2(3x)^2/(3x+3y)=18x^2/3(x+y)=6x^2/(x+y)

(x+y)分之(x的平方-xy+y)是最简分式;

x/y=2则x=2y代入下式(x^2+y^2)/xy=（4y^2+y^2）/(2y^2)=5/2