x-2 y=9 3 x-2 y=0 解二元一次方程组
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(x+y)(x-y)-(x+y)=0(x+y)(x-y-1)=0若x-y-1=0y=x-1则4x^2-x^2+2x-1+2x-x+1=03x^2-3x=03x(x-1)=0x=0,x=1y=x-1若x
Dx^y+x^-y=2根号2===>(x^y+x^-y)^2=8===>x^2y+x^-2y+2=8===>x^2y+x^-2y=6(x^y-x^-y)^2=x^2y+x^-2y-2=6-2=4==>
原式化简为:(x+1)平方+(y-2)平方=0,因为(x+1)平方,(y-2)平方都大于或等于0,所以(x+1)平方,(y-2)平方都为0,所以x=-1,y=2,所以(x+y)2012次方为:(-1+
A∩B只有一个元素说明函数y=-x²+mx-1和y=3-x在[0,3]内只有一个交点可分两种情况1,y=-x²+mx-1和y=3-x有且只有一个交点此时,联立化简得x²-
(2x-5y=1)乘以2(5x+2y=17)乘以5两式相加解出x=3,代入解出y=1同理解第二个方程
解1:由式1,得6x-6y-7x-7y=21即-x-13y=21a式由式2,得2x-2y-5x-5y=-1即3x+7y=1b式由a式乘以3加上b式,得-39y+7y=63+1解得y=-2代入a式,得x
(x*x+y*y)(x*x+y*y)-4x*x*y*y=(x^4-2x^2y^2+y^4)=(x^2-y^2)^2=0x^2=y^2x/y=±1(x*x+5xy+y*y)/(x*x+2xy+y*y)=
X+Y分之X-Y等于3x=-2yX+Y分之2(x-y)减X+Y分之3X+Y=(-x-3y)/(x+y)=1
再答:不对再答:
因为(x-y)/(x+y)=3,则(x+y)/(x-y)=1/3则5(x-y)(x+y)-(x+y)/2(x-y)=5*3-1/(3*2)=15-1/6=89/6
先一个一个的展开括号项,再同项合并就行了啊[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x=[xx-xy-(xy-yy)+x(x-y)+y(x-y)]÷2x=[xx-xy-xy+yy+xx-
X^2表示平方X^2+4X+4+Y^2-2Y+1=0(X+2)^2+(Y-1)^2=0因为平方大于=0所以X+2=0Y-1=0X=-2Y=1X^2+Y^2=5
即(x-2y)²=0x-2y=0所以x=2y所以原式=(2x²+2xy-xy-y²)/(4x²-4xy+y²)=(2x²+xy-y²
令a=2x-y,b=x+y用ab表示不等式,有4/3a-2/3b=01/3(a+b)
一,x=25,y=15二,x=-2,y=5再问:步骤
设该二元函数为g(x,y),则g'x(x,y)=xy(x+y)-f(x)y两边对x求积分g(x,y)=x³y/3+x²y²/2-y∫f(x)dxg'y(x,y)=f'(x
一、3x-5y=5……①3x-4y=23……②②-①得,y=18,把y=18代入①得,x=95/3∴x=95/3y=18二、2x-7y=8……①3x-8y-10=0……②①×3得,6x-21y=24…
(线性规划)由条件当X=Y=3时有最大值Z=6即得K=3再由X+2Y>=0很容易求得Z最小值-3
展开x^2-2y^2-xy=-5x^2-2y^2+xy=7所以x^2-2y^2=1xy=6上式除以下式,解分式方程x/y=3/2或-4/3(舍去)所以x^2=9y^2=4x=3y=2或x=-3y=-2