2x y等于6,x-3y等于1-搜答案-大师作文网

xy=-2x-y=-3-6xy-10y+10x=12-10(y-x)=12+30=42

1/x-1/y=2y-x=2xyx-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=[-6xy+7xy]/[-4xy-3xy]=xy/[

3x^2y-xy^2=xy(3x-y)将x=-1/2y=1代入有-1/2*1*[3*(-1/2)-1]=-1/2*(-5/2)=5/4

(3x+2y)(2x+y)-6x(x+1)大于等于7xy+2y^2-2==>6x^2+7xy+2y^2-6x^2-6x>=7xy+2y^2-2==>消除合并后可得==>-6x+2>=0==>x

通分1/x-1/y=(y-x)/xy=3y-x=3xyx-y=-3xy原式=[(x-y)-2xy]/[5(x-y)+3xy]=(-3xy-2xy)/(-15xy+3xy)=-5xy/(-12xy)=5

（5xy-2x^2）-3xy-2（3xy-4x^2）=5xy-2x^2-3xy-6xy+8x^2=-4xy+6x^2x等于1,y等于-2原式=-4*1*（-2）+6*1^2=8+6=14

1/X-1/Y＝5（Y-X）/XY＝5Y-X＝5XY（3x+7xy-3y）/（2x-3xy-2y）＝[3（X-Y）+7XY]/[2（X-Y）-3XY]＝[-3（Y-X）+7XY]/[-2（Y-X）-3

解析：

x分之1减y分之1等于2（y-x）xy=2y-x=2xyy减xy减x分之3x加xy减3y=[3(x-y)+xy]/(y-x-xy)=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5

(x+y)(x-y)-(x的2次方-3xy)=x²-y²-x²+3xy=3xy-y²=3x2x(-1/2)-(-1/2)²=-3-1/4=-3.25

4x+2xy+y等于

题出错了吧

x^2减6xy加9y等于0.则x：y等于_3:1___.

2(x+xy)-[(xy-3y)-x]-(-xy)=2x+2xy-xy+3y+x+xy=3x+3y+2xy=3（x+y）+2xy=3*（-2）+2*3=0

3x²-xy+y²=101-xy+4y²=421-2得3x²-3y²=6x²-y²=2选B

因为1/x+1/y=-3所以(x+y)/xy=-3即x+y=-3xy所以(x-6xy+y)/(3x+2xy+3y)=(-3xy-6xy)/[3(x+y)+2xy)]=-9xy/(-9xy+2xy)=9

1/x-1/y=3则x-y=-3xyx-3xy-y/2x-xy-2y=(-3xy-3xy)/(-6xy-xy)=6/7

1/x-1/y=2(y-x)/xy=2y-x=2xy(3x+5xy-3y)/(x-xy-y)=[5xy-3(y-x)]/[-xy-(y-x)]=(5xy-6xy)/(-xy-2xy)=-xy/-3xy

y/x=1/3所以x=3y原式=x(3x+y)(3x-y)/(3x+y)(3x-y)²=x/(3x-y)=3y/(3×3y-y)=3y/8y=3/8

设x+y=axy=b,则b/a=3b=3a所以-X+3XY-Y分之2X-3XY+2Y可以写成(2a-3b)/(3b-a)=-7/8

-3（2x^2-xy-6）貌似这个式子化不化简没有关系呢原式=-3（2*1^2-1*2-6）=-3(4-2-6)=12