3x+5y≥70,7x+2y≥86,10x+7y≥185 求x y是多少

3x+5y≥70,7x+2y≥86,10x+7y≥185 求x y是多少 求f(x,y)=x+y+7的最大值,使(x,y)满足x+2y≤10,2x+y≥6,y≥0 5x^3y(x-y)^3-10x^4y^3(y-x)^2因式分解 5x^3y(x-y)^3-10x^4y^3(y-x)^2 (x+5y)^+(2x+10y)(3x-y)+(3x-y)^ (x+5y)²-(2x+10y)(3x-y)+(3x-y)² 5X^3Y(X-Y)-10X^4Y^3(Y-X)^2因式分解 化简:3(x-y)²-7(x-y)+ 2(x-y)²+5(x-y) x-y/7 - x+y/10 =1/2 2(x-y)-5(x+y)=3修改、、、、（x-y)/7-(x+y)/10=1/2 2(x-y)-5(x+y)=3 计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 { x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3 y满足x-y+2≥0,x+y-4≥0,2x-y-5≤0 求X^2+Y^2-10Y+25的最小值 已知x.y满足(x-y-2≤0,x 2y-5≥0,y-2≤0 则3x+y/x+1得多少 已知变量x,y满足约束条件2x-y≤0,x-3y+5≥0,求10^(x+y-1)的最大值 化简3(x-y)-7(x--y)+2(y-x) 化简:5(x-y)+2(x+y)-3(x-y) (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuaihuajian