20÷x=y+2 xy各等于几？

xy+xy=20,x=,y=

已知x-xy=20,xy-y=-10 两式相加得x-y=10 两式相减得x+y-2xy=30

x÷20=y,x与y成什么比例?

正比例

20除以几等于几分之12?

设20除以x等于y分之12则:20/x=12/y即:20y=12x5y=3xy=3x/5这是一条直线,有无穷多解比如:x=5,y=3x=10,y=6x=15,y=9……

X除1/2等于y除2/3,XY等于多少

X÷1/2=Y÷3/2,2X=2Y/3,X=Y/3,X/Y=1/3,(X:Y=1:3).

[(xy - 2)( - xy - 2) - 4(xy - 1)^2]除以( - xy),其中x=20,y= - 25分之1

[(xy-2)(-xy-2)-4(xy-1)²]/(-xy)=[-(x²y²-4)-4(xy²-2xy+1)]/(-xy)=(-5x²y²+8xy-1)/(-xy)=5xy-8+1/xyx=20,y=-25分之1 xy=20*(-1/25)=-4/5原式=5*(-4/5)-8+(-5/4)=-4-8-5/4=-53/4

X+Y=30,X除以Y=3,XY各是多少?

X+Y=130,X除以Y=3;X=3Y 4Y=130 Y=32.5 X=67.5

xy=36,x÷y=4,请问x.y各是多少

=36÷4y²:4y*y=364y²=36y²xy=36x÷y=4即x=4y把x=4y代入xy=36,x=4y=4*3=12当y=-3时;=9y=3或者-3当y=3时再看看别人怎么说的.

X+y=43 x - y=3 求xy各等于多少

(x+y)3(x-y)-(x+y)(x-y)3=(x+y)(x-y)[(x+y)²-(x-y)²]=(x+y)(x-y)(x+y+x-y)(x+y-x+y)=4xy(x+y)(x-y)

x - y=5 x+y=20问x.y各等于多少

x-y=5 ①式x+y=20 ②式②式+①式x+y+ⅹ-y=20+52ⅹ=25ⅹ=25÷2x=12.5y=20-12.5y=7.5

x+y等于28100.15除以20求x和y得多少

x、y有无数组数值,y最小=20+1=21,这时x最小=21*3+20=83.