- #1
astenroo
- 47
- 0
Homework Statement
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.
Homework 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
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