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Linear Algebra Problem concerning a circuit

  1. Jul 7, 2007 #1
    1. The problem statement, all variables and given/known data

    http://img216.imageshack.us/img216/302/problem8310en9.jpg [Broken]

    By applying Kirchoff's laws to the circuit above, we obtain the following equations:






    Obtain the solution set of equations by Gauss elimination. If there is no solution, or if there is a non-unique solution, explain that result in physical terms.


    2. Relevant equations

    Linear algebra, matrices, etc.

    3. The attempt at a solution

    First, I put the four non-identical equations into a matrix.


    Now I reduce it down to R.R.E.F. using elementary row operations. (Note that one of the equations is redundant)


    So then, [itex]i_1\,=\,\frac{2E}{3R}[/itex] and [itex]i_2\,=\,i_3\,=\,\frac{E}{3R}[/itex]?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jul 7, 2007 #2


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    Look fine to me.
  4. Jul 8, 2007 #3
    yeah, that's right but in the initial equations, it should be:
    I2R2 + I1R1=E
    I3R3 + I1R1 = E
  5. Jul 8, 2007 #4


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    True. But the signs were correct in the matrix. Took it as a typo.
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