运筹学……对偶问题。

Question

maxz=x1+2x2+3x3+4x4
-x1+x2-x3-3x4=5
6x1-7x2+3x3-5x4<=8
12x1-9x2-9x3+9x4<=20
x1.x2>=0 x3<=0 x4无约速

Answer 1

min z = 5y1+8y2+20y3
s.t.
-1y1+6y2+12y3 >=1
y1-7y2-9y3 >=2
-1y1+3y2-9y3 <=3
-3y1-5y2+9y3 =4
y1 无约束，y2，y3 >=0