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Homework Help: Kirchoff loop question

  1. Nov 2, 2008 #1
    My professor gave us the three equations for a circuit and said to find I1, I2, and I3 However, I cannot figure out how to solve it.

    The equations:

    I1 + I2 = I3

    5 - 10*I1 -10 - 5*I3 = 0

    5 - 5*I2 - 5*I3 - 10 = 0

    Every time I try to solve it I end up with two unknown variables. How would you solve them? I am having difficulty solving systems of equations. A step by step guide would be a great help.
    Last edited: Nov 2, 2008
  2. jcsd
  3. Nov 2, 2008 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Try substituting the the first equation into the second and third equations to eliminate I3. You will then have two equations with two unknowns, which you can solve my eliminating a further variable.

    Alternatively if you are comfortable with matrices you can form a matrix equation and put the coefficient matrix into REF.
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