已知一个分式乘负y分之2x的3次方-搜答案-智慧作业帮

设k.x=2k,y=3k原式=-12/5

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

由　1/X-1/Y=5,两边同乘　XY,得出Y-X=5XY,那么　　分子　-X+XY+Y=6XY分母　2X+7XY-2Y=7XY-2(Y-X)=-3XY　　得此分式的值为－2

-12后有没有x

题有错吧,没负号吧

x+3y=0；x=-3y；x/y=-3;负x-2y分之负x加2y=(-x+2y)/(-x-2y)=(-x/y+2)/(-x/y-2)=(3+2)/(3-2)=5;很高兴为您解答,skyhunter00

x-3y=0x=3y2x+y/x^2-2xy+y^2×(x-y)=(2x+y)/(x-y)^2*(x-y)=(2x+y)/(x-y)=(6y+y)/(3y-y)=7y/2y=7/2

3y2-2y+6=8,除以3得y2-2/3y+2=8/3,得y2-2/3y＝2/3,-y2+2/3y＝-2/3,-y2+2/3y+3＝-2/3+3＝7/3

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

只要把负号移到分数前去

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

x^2-2xy+y^2+y^2-y+1/4=0(x-y)^2+(y-1/2)^2=0(x-y)^2>=0(y-1/2)^2>=0(x-y)^2+(y-1/2)^2>=0(x-y)=0(y-1/2)=0

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

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

-2/5

题目是否有错?是求x^2减4分之9y^2的值吧因为9^x*27^（-y)=1即：（3^2）^x*(3^3)^(-y)=13^(2x)*3^(-3y)=13^(2x-3y)=1所以2x-3y=0所以x=