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398                Chapter  Ten:  Linear  Programming


            There  are  four  basic  feasible  solutions,  i.e.,  extreme  points.
            The  one that  produces  the  largest  value of,zis:r  =  0,y  =  10,
            giving  z  =  20.  Thus  x  =  0,  y  =  10  is an  optimal  solution.



            Exercises   10.3

                 In  each  of  the  following  linear  programming  problems,
            transform  the problem to canonical  form  and determine  all the
            basic  solutions.  Classify  these  as  infeasible  or  basic  feasible,
            and  then  find  the  optimal  solutions.

            1.
                 maximize:  z  =  3x  —  y
                              (  x  +  3y   <  6
                 subject  to:  <  x  —  y   <  2
                              {    x,y>0
            2.
                 maximize:  z  =  2x  + 3y
                              (  2x-y      <   6
                 subject  to:  <  2x  + y  <   10
                              [x,y>0
            3.
                 maximize:  z  =  X\  + x-i + X3
                          {       4xi  + -  2x 2  +  4x 3  < <  12
                                           x 2+
                                   2x x
                                                               4
                                                    5x3
                                               > 0
                                     xi,x 2,x 3
            4.  A  linear  programming   problem  in  standard  form  has  m
            constraints  and  n variables.  Prove that  the number  of extreme
                                         n
            points  is at  most  YlT=o (™^ ) •
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