8-x>0 s·tx4=7-2x20 xs=9-3x2>0 取 87919 时,有x、=9-3x,=0 于是,把x2与x的地位互换即应在约束条件中用xx来 表示x2x32x将(71)的约束变形为 5-2x1+-x x1+-x (7.4) 3 3 5x3 = 8－x2≥0 x4 = 7－2x2≥0 (7.3) x5 = 9－3x2≥0 于是,把x2与x5的地位互换,即应在约束条件中用x1 ,x5来 表示x2 , x3 , x4 . 将(7.1)的约束变形为 (7.4) 9 3 0. 3 9 3 9 , 2 7 , 1 8 2 min 5 = − 2 =    =    取x = 时，有x x      s t          = − = − + = − + 2 5 4 1 5 3 1 5 3 1 3 3 2 1 3 1 5 2 x x x x x x x x