已知 x-7 y 13 =0 求x y的值-搜答案-搜搜做题作业网

x/2=y/3x=2y/3所以x²-2xy-3y²/x²-6xy-7y²=(x+y)(x-3y)/(x+y)(x-7y)=(x-3y)/(x-7y)=(2y/3

x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17

3x*+xy-2y*=0（3x-2y）(x+y)=0那么x=2y/3或x=-yy/x=3/2或x/y=-1(x/y)-(y/x)-(x*+y*)/(xy)=(x/y)-(y/x)-(x/y+y/x)=

由y=3xy+x得x-y=-3xy2x+5xy-2y/x-2xy-y=2（x-y）+5xy/x-y-2xy=-6xy+5xy/-3xy-2xy1/5

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

原式=6x+4xy+2xy+3x+2y-4xy+7y=9x+9y+2xy=9(x+y)+2xy=9×4+2×2=36+4=40

5xy+4x+7y+6x-3xy-4xy+3y=5xy-3xy-4xy+4x+6x+7y+3y=（5-3-4）xy+（4+6）x+（7+3）y=-2xy+10x+10y=-2xy+10（x+y）因为x

(xy)²-xy-2=0(xy-2)(xy+1)=0xy=2或者-1施主,我看你骨骼清奇,器宇轩昂,且有慧根,乃是万中无一的武林奇才.潜心修习,将来必成大器,鄙人有个小小的考验请点击在下答案

先把代数式（5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)化简（5XY+4X+7Y)+(6X-3XY)-(4XY-3Y)=5XY+4X+7Y+6X-3XY-4XY+3Y=-2XY+10X+1

y-x-2xy=0所以x-y=-2xyy-x=2xy所以原式=[3(x-y)+xy]\[(y-x)-xy]=[3×(-2xy)+xy]\(2xy-xy)=-5xy\xy=-5

x²-10x+25+|y-3|=0(x-5)²+|y-3|=0所以x=5,y=3代入计算即可

x²-7xy+12y²=(x-4y)(x-3y)=0x=4y或x=3yx=4y时(x²-xy+y²)/2xy=(16-4+1)y²/8y²=

再答：采纳一下，好吗？谢谢了再问：可是答案上的结果是0或负一哦再答：-1显然是错误的

x²-7xy+12y²=0,(x-4y)(x-3y)=0x=4y或x=3yy分之x=4或3.已知x²y²-20xy+x²+y²+81=0,x

16524

3(x^2-xy)-xy+y^2=3(x^2-xy)-(xy-y^2)=3*5-(-3)=15+3=18

x^2-7xy+12y=0,且x.y不等于0(x-3y)(x-4y)=0x=3y或x=4y(x^2-2xy+y^2)/(2xy)=(x-y)^2/(2xy)x=3y时原式=4y^2/(6y^2)=2/

x²-7xy+12y²=0(x-3y)(x-4y)=0x1=3yx2=4yx=3y时原式＝9y²-3y²+y²/6y²=7/6x=4y时原式

∵x-y=4xy∴原式=[2(x-y)+3xy]/[-(x-y)-2xy]=(8xy+3xy)/(-4xy-2xy)=11xy/(-6xy)=-11/6

原式=（x-3y）（x-4y）=0所以x=3y或x=4y所以y/x=1/3或y/x=1/4因式分解用十字相乘法,初二的应该会