# D1 simplex and linear programming facts help

Watch
Announcements
#1
It's not that I stuggle with the process of producing a simplex table and doing iterations.
Or using inequalities to find the feasible region on a graph for linear programming.
It's the understanding part of them that I dont get:
• How can would you know if the maximum equation is finite or not
• Why can't you pivot on columns that are all negative

Are there any more facts that I need to know about Simplex or Linear Programming? If there's any sort of resource that points out all of these facts that'll be helpful. I'm getting tired of missing out 3/4 marks on questions like these which are purely just fact based
0
#2

Parts VI and IV confuse me, I never thought about finite values when it came to simplex. I obviously checked the markscheme, and showed me how to answer it. But I want to understand it a bit more in depth about it for when another question like this one comes up.
0
#3
PING
0
#4
Well, from the looks of things, the TSR Maths community really is avoidant of D1 problem solving, CMON BOIS
0
3 years ago
#5
Whether P is finite is just a question of looking at the constraints and the profit equation, notice that the constraints allow you to make z as large as you want, and therefore you can make P as large as you want.

Its part of the algorithm where you pick the smallest positive value of the theta values when picking your pivot row, so if there arn't any positive values there, you can't pivot on a cell from that column. I'm not sure but I think this has something to do with the simplex algorithm only dealing with positive values, and if you pivot on a negative cell, the value of the variable is then negative
1
#6
(Original post by alfredholmes)
Whether P is finite is just a question of looking at the constraints and the profit equation, notice that the constraints allow you to make z as large as you want, and therefore you can make P as large as you want.

Its part of the algorithm where you pick the smallest positive value of the theta values when picking your pivot row, so if there arn't any positive values there, you can't pivot on a cell from that column. I'm not sure but I think this has something to do with the simplex algorithm only dealing with positive values, and if you pivot on a negative cell, the value of the variable is then negative
THANKS ALFRED!
It's seems that the answer just right in front of me all this time, hopefully I dont make these sorts of silly mistakes in the actual exam!
1
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Current uni students - are you thinking of dropping out of university?

Yes, I'm seriously considering dropping out (95)
13.85%
I'm not sure (32)
4.66%
No, I'm going to stick it out for now (215)
31.34%
I have already dropped out (16)
2.33%
I'm not a current university student (328)
47.81%