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Non linear equation question

  • 24-02-2008 7:29pm
    #1
    tywy
    Closed Accounts Posts: 1,240 ✭✭✭


    Ok, so I have a feeling I should already know this but I'll ask anyway. I have 4 simultaneous equations I wish to solve numerically. I assume I have to use some numerical method but I don't know which. The equations look something like this...

    2 - 3A + 4AB +C = 0

    2AB - 3C = 0

    3C - DE - F =0

    2DE - 3F =0

    They actually full of decimals so I'm not gonna type out the exact ones. Don't want people to solve them for me just need a nudge in the right direction. Thanks!


Comments

  • #2
    MathsManiac
    Registered Users, Registered Users 2 Posts: 1,595 ✭✭✭MathsManiac


    You've got 6 unknowns and only 4 equations, so there isn't a unique solution. D and E are tied together as DE, so you could treat that as one variable. But that still leaves you one equation shy, which means the best you can gope for is to get all the remaining variables in terms of one of them.

    Use eqns 3 and 4 to get rid of DE. use 1 and 2 to get rid of AB (which gets rid of B for you. Now you'll have two equations in three enknowns: A, C and F, and they're linear, so you should be able to write everything in terms of one of them (say A).

    Of course, when you're finished, DE will still be locked together.


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