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The system that I need to solve is $$ \begin{align} &i_1 + i_2+ i_3 &=0\\ &i_1+i_4+i_6 &=0\\ &i_5+i_6&=i_2\\ &-v_{s1} + i_1r_1 + i_3r_3 - i_4r_4 + v_{s4} &= 0\\ &-i_2r_2 + v_{s2} - i_5r_5 - i_3r_3 &= 0\\ &-v_{s4} + i_4r_4 + i_5r_5 - i_6r_6 - v_{s6} &= 0\ \end{align} $$ for the variables $i_k$.

For the asker: the question as it should appear

enter image description here

You can see the original question at: http://fourier.eng.hmc.edu/e84/lectures/ch2/node2.html :example 2. Please provide the steps. Thank U in advance.

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What are the variables ? One way is to compute a Groebner basis (i suppose the system is quadratic, and not linear). –  Dietrich Burde Aug 21 '13 at 13:30
    
We have to find i1,i2,i3,i4,i5,i6. –  Ekagra Aug 21 '13 at 13:34
    
This is a system of 6 linear equations in 6 unknowns. You can find methods in any linear algebra textbook, or online by searching for "system of linear equations". –  Gerry Myerson Aug 21 '13 at 13:41
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Someone took the time to format your wretched question decently, and you rolled it back! Why would you do such a thing? –  Gerry Myerson Aug 21 '13 at 13:45
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What have you already tried? What do you know about systems of simultaneous equations? Also, please take the time to learn how to format your questions properly: meta.math.stackexchange.com/questions/5020/… –  Rhys Aug 21 '13 at 13:48
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1 Answer 1

up vote 0 down vote accepted

For convenience, let's rewrite the system as $$ \begin{align} &i_1 &&+ i_2 &&+ \,\,\,\,i_3 &&&&&&&&=0\\ &i_1 &&&&&&+i_4&&&&+i_6 &&=0\\ &&&-i_2&&&&&&+i_5&&+i_6&&=0\\ &r_1i_1 &&&&+r_3i_3 &&-r_4i_4 &&&&&&= v_{s1}-v_{s4}\\ &&&-r_2i_2 &&- r_3i_3 &&&&-r_5i_5 &&&&= -v_{s2}\\ &&&&&&& +r_4i_4 &&+r_5i_5 &&-r_6i_6 &&= v_{s4}+v_{s6}\ \end{align} $$ (the above should look like this):

$\hspace{14mm}$enter image description here

From there, you should be able to use Gaussian elimination

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What have you written.I cannot understand –  Ekagra Aug 21 '13 at 13:44
    
I just rewrote the system of equations so that the variables we want to solve for are lined vertically lined up. –  Omnomnomnom Aug 21 '13 at 13:45
    
The phrase, "multiplication-addition", means nothing to me, and I've been teaching Linear Algebra for 35 years. –  Gerry Myerson Aug 21 '13 at 13:46
    
@GerryMyerson after googling, I realize that not everyone uses the same term for it. That's the term I heard for Gaussian elimination before I was told it was Gaussian elimination. –  Omnomnomnom Aug 21 '13 at 13:48
    
Why has anybody given me 2 vote downs? –  Ekagra Aug 21 '13 at 13:51
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