百度作业网x y≥3,x-y≥-1,2x-y≤3,ax y=z的最小值为
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/13 02:23:04
xy(xy+1)+(xy+3)-2(x+y+1/2)-(x+y-1)^2=xy(xy+1)+(xy+1)+2-2(x+y)-1-[(x+y)^2-2(x+y)+1]=(xy+1)^2+2-2(x+y)
=-x-(2y-2+3x)+2(x+4)=-x-2y+2-3x+2x+8=-4x-2y+10
(x+y-2xy)(x+y-2)+(1-xy)^2=(x+y)^2-2(1+xy)(x+y)+4xy+1-2xy+x^2y^2=(x+y)^2-2(1+xy)(x+y)+(1+xy)^2=(x+y)^
3xy[2xy-x(y-2)+x-1]=3xy(2xy-xy+2x+x-1)=3xy(xy+3x-1)=3x^2y^2+9x^2y-3xy
5x^2y/-1/2xy*3xy^2=-7.5x²y²
(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)=-6xy+3x-3y=-6×(-2)+3×1=15
(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3=-(x-y)^3[-(xy-5)/x^2(x-y)]/[(xy-5)/xy]=(x-y)^3(xy-5)xy/x^2(x-y)(x
原式=3x-3y-6xy=3-12=-9
原式=3x(xy-2x/y+2x²/3)+3x²y-3y³=3x²y-6x²/y+2x³+3x²y-3y³=2x
作图易知可行域为一个三角形，当直线z=3x+y过点A（3，-2）时，z最大是7，故答案为：7．
3/(x-y)=1/xyx-y=3xyy-z=-3xy原式=[(y-x)-2xy]/[2(x-y)+3xy]=[(-3xy)-2xy]/[2(3xy)+3xy]=-5xy/9xy=-5/9
(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)=-2xy+2x+3y-3xy-2y+2x-x-4y-xy=-6xy+3x-3y=-6xy+3*(x-y)当时,原式=-6*1+3*
原式(-xy/3)²*[xy(2x-y)-2x(xy-y²)]=(x²y²/9)(2x²y-xy²-2x²y+2xy²)
原式=1/2xy-{1/2xy-[1/3x^2y-x^2y+xy]+1/3x^2y}&&去小括号=1/2xy-{1/2xy-[-2/3x^2y+xy]+1/3x^2y}=1/2xy-{1/2xy+2/
（x+2y-3xy)-(-2x-y+xy)=x+2y-3xy+2x+y-xy=(1+2)x+(2+1)y-(3+1)xy=3x+3y-4xy=3(x+y)-4xy=3*1/2-4*(-1/2)=3/2
因为xy/（x+y）=1/2所以x+y=2xy原式=3（x+y)-5xy/(-x-y+3xy)=3*2xy-5xy/(-2xy+3xy)=xy/xy=1
y^3+xy^2+2xy+x^2-1=(x+y-1)(x+y^2+y+1)再问：烦写出过程再答：
1、(-7x^y)(2x^y-3xy^3+xy)=-14x^(2y)+21x^(y+1)y^3-7x^(y+1)y;2、((x-y)^6)/((y-x)^3)/(x-y)=-(x-y)^3/(x-y)
原式=-x²y+2xy²+2x²y²-4xy³-3x³+27x³y-18x²y²+2x²y-18x&
(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)=-2xy+2x+3y-3xy-2y+2x-x-4y-xy=-6xy+3x-3y=-6*(-2)+3*1=15不懂可追问,有帮助请采