当x减y等于负一xy等于1球a减2b-搜答案-搜搜做题作业网

解a=2x²+3xy-2x-1b=-x²+xy-13a+6b=15xy-6x-9=3x（5y-2）-9的结果与x无关,则5y-2=0y=2/5

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

x²+xy=2xy+y²=-1两式相减得：x²-y²=3两式相加得：x²+2xy+y²=1

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

A=2-3y+2-1=3-3yB=-1-y-1=-y-23B=-3y-6A-3B=3-3y+3y+6=9

x等于0y等于2.5xy等于0..

(1/x+1/y)^2=251/x^2+2/xy+1/y^2=251/x^2+1/y^2=27(1/x^2+1/y^2)^2=7291/x^4+1/y^4+2/x^2y^2=7291/x^4+1/y^

x+y=-5【1】xy=6【2】由【1】得x=-5-y【3】把【3】代入【2】得（-5-y）y=6-5y-y²-6=05y+y²+6=0y=-2或-3得x=-3或-2x²

设y1=k1x²,y2=k2(x-2)∵y=y1+y2∴y=k1x²+k2(x-2)根据题意得5=k1-k211=k1-3k2∴k1=2k2=-3∴y=2x²-3(x-2

（x-y）²=（x+y）²-4xy=25-12=13

(xy)^-2=1/(xy)²=1/x²y²(x+y)^-2=1/(x+y)²=1/(x²+2xy+y²)

已知A=x³+2y³-xy²,B=-y³+x³+2xy²,其中x等于1\3,y等于2A-B=（x³+2y³-xy

2(x﹢y)﹦-6,x+y=-3(x﹢2)-(3xy-y)=x+y-3xy+2=-3-3+2=-4ax^3+bx^5=-9,x=-1,a+b=9ax^3+bx+5=-a-b+5=-9+5=-4设5月x

y=ax²+bx-1当x=1时,y=-2得-2=a+b-1①当x=2时,y=-1-1=4a+2b-1②②-①*2,得a=1将a=1代入①,得b=-2则a=1b=-2当x=3时,y=9-6-1

x=10y=11x^2=100(-y)^2=121x+y=21x=1y=1/2x^2=1(-y)^2=1/4x+y=3/2x=5y=-6x^2=25(-y)^2=36x+y=-1从上面式子中可以看出,

若你的题目是这样的：x+y=3xy=-3,求（1-y)(1-x)那么解题如下：首先这道题目不用把x、y解出来,只要变化一下式子就好因为3xy=-3所以xy=-1又因为x+y=-3把（1-y)(1-x)

那就会等于-7X+5(X+Y)-3xy-10y=5(x+y)-10XY-10Y=5(x-y-2xy)=-35再问：7X去哪里了，10xy那一步没看懂再答：打错了，应该是-7XY+5(X+Y)-3xy-

原式=5x-3y-2xy-6x-5y+2xy=-x-8y把x=-5,y=-1代入得原式=5+8=13

x^2-xy=14xy-3y^2=2求x^2+3xy-3y^2因为x^2-xy=1所以x^2=1+xy带入原式得4xy+1-3y^2因为4xy-3y^2=2将其带入原式得2+1=3

x=2/3,y=-3/4,then?