(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The currents in a DC circuit is to be calculated, and I end up with a system of 5 equations and 5 unknowns. This is where my headache starts.

2. Relevant equations

(1) I[tex]_{1}[/tex]=I[tex]_{2}[/tex] + I[tex]_{3}[/tex]

(2) I[tex]_{2}[/tex]=I[tex]_{4}[/tex] + I[tex]_{5}[/tex]

(3) 6 - 2I[tex]_{1}[/tex] - I[tex]_{3}[/tex] = 0

(4) 4.5 - 5I[tex]_{2}[/tex] - 3I[tex]_{5}[/tex] + I[tex]_{3}[/tex] = 0

(5) 3I[tex]_{5}[/tex] - 3I[tex]_{4}[/tex] -3 = 0

3. The attempt at a solution

Now, I have no problem solving equations with two unknowns. But 5?

Anyway, I gave it a try. I tried to substitute (2) in (1) and substituting the result into (3) and then substituting (2) into (4), resulting in a new system with three unknowns

(3') -3I[tex]_{3}[/tex] - 2I[tex]_{4}[/tex] - 2I[tex]_{5}[/tex] = -6

(4') I[tex]_{3}[/tex] - 5I[tex]_{2}[/tex] - 8I[tex]_{5}[/tex] = -4,5

(5') -3I[tex]_{5}[/tex] + 3I[tex]_{5}[/tex] = 3

I've been on this problem for the last 6 hours and I still haven't figured out how to solve it.

I've even tried using a matrix (never done one before today), and it all goes wrong, since I apparently don't know how to use a matrix :P

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# Homework Help: Needing help with calculating currents

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