y等于x(1-2x)
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x²+y²+1≤2x+2y(x²-2x+1)+(y²-2y+1)≤1(x-1)²+(y-1)²≤1由于(x-1)²≥0、(y-1)
X=-2,Y=-6再问:过程再答:第二个方程解开:X2+2X-4Y2+4=X2-4Y2x=-2,再带入第一个方程得Y=-6
由意义,画出线性规划图,可以看出满足条件的解x>0,y>0.则z=(x+2y)/(2x+y)=[(x+y/2)+3y/2]/(2x+y)=1/2+3y/(4x+2y)=1/2+3/(4x/y+2).其
根据3组不等式约束,画出x,y的取值区域z=x+2y看成一条直线,平移直线过x,y的取值区域即可得最大最小值
原式=1/2x-[1/(x+y)][(x+y)/2x-(x+y)]=1/2x-[1/(x+y)](x+y)(1/2x-1)=1/2x-(1/2x-1)=1/2x-1/2x+1=1
线性规划就行了,你学了吗?
X+Y≥2⑴2X-Y≤1⑵X-Y≥0⑶⑴+⑶X≥1⑶×-1Y-X≤0⑷⑵+⑷X≤1所以X=1代入⑶Y≤1所以2X+3Y≤5
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==>
=x^2+4y^2+1+4xy-4y-2x
(x+2y-1)(x-2y+1)-(x+2y+1)(x-2y-1)=[x+(2y-1)][x-(2y-1)]-[x+(2y+1)][x-(2y+1)]=x²-4y²+4y-1-(x
9用线性规划就行了
华师一附中28班高手教你.A中可化为y=x1且X不等于2即B比A多一个元素(2,3)CuA包含(2,3)所以(CuA)交B等于(2,3)
x-y/x+y=1/2设:x=3y=1代入可得:(y-x/x+y)-(2x+2y/x-y)=-4(1/2)
1)x(x-y)(x+y)-x(x+y)^2=x((x-y)(x+y)-(x+y)^2)=x(x^2-y^2-x^2-2xy-y^2)=x(-2xy-2y^2)=-2xy(x+y)2)(2a+b)(2
(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
x+y>=0x-y>=0所以,两式相加,得2x>=0,x>=0又y>=-x,y
x方-y方+2x+1=(x^2+2x+1)-y^2=(x+1)^2-y^2=(x+y+1)(x-y+1)