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    This may sound like a stupid question, but i'm doing a piece of work for Economics on linear programming. The last part of the question requires you to introduce a third output, but how can I do this given that there are only 2 axis?

    The only linear programming I have done involved only 2 outputs, x and y.. I have no idea how to introduce a third?
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    What linear programming method are you using? You can have any number of variables in a linear program; you're only restricted by two when you are trying to draw the system on a two-dimensional graph.

    Can you provide a bit more info on what you've done so far/what you're trying to do?
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    We're using Excel & Solver (which i've never used before for this type of thing). This is the question:

    In the accompanying EXCEL spreadsheet is an example of linear
    programming with SOLVER already set up. Interpret the x variables as the
    outputs of a company, and the elements of the b vector as the fixed stocks of
    inputs. Interpret the c vector coefficients as the selling prices of the outputs
    and the A matrix coefficients as the input requirements per unit of output –
    see lecture 6 example. Make up new values for each of the coefficients:
    ? change the values in c showing the effects of different selling prices on
    the choice of output levels
    ? change the values in A showing the effects of different technological
    processes and constraints
    ? and change the values in b showing the effects of different input levels
    Solve the programme in each case using SOLVER. Interpret your answers,
    Illustrate your solution graphically using EXCEL.
    ? Introduce an extra constraint and comment on its impact
    ? Introduce an extra output with corresponding price and input-output
    coefficients and comment on how your SOLVER set-up has changed
    (Original post by Planto)
    What linear programming method are you using? You can have any number of variables in a linear program; you're only restricted by two when you are trying to draw the system on a two-dimensional graph.

    Can you provide a bit more info on what you've done so far/what you're trying to do?
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    Not all that familiar with using Excel for LP, but I'm presuming that you have sets of cells corresponding to your various vectors etc.

    Sounds like all you need to do is add in an arbitrary new x value and its corresponding profit value as a new c coefficient, add any new necessary constraints (including, presumably, x_i \geq 0) and include these new values when calculating your solution.

    You won't be able to represent a linear program with more than two x variables on a two-dimensional graph but it should still solve in the same way.
 
 
 
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