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## Homework Statement

I am having trouble determining the error for a set of linear equations that represent a simple circuit with two voltage sources. I have found two possible uncertainties by solving using substitution, detailed below.

The circuit is shown below:

http://img233.imageshack.us/img233/9165/circuit1small.jpg [Broken]

## Homework Equations

I am solving the circuit using loop analysis and the two equations found are:

1. I1R1 + R2(I1+I2) = V1

2. I2R3 + R2(I1+I2) = V2

## The Attempt at a Solution

Solving 2. for I2 and subbing into 1. gives:

I1 = 25.8 mA +- 17.2%

Solving by back subbing into 2. gives:

I2 = 128.5 mA +- 6.1%

or subbing I1 into 1. gives:

I2 = 128.5 mA +- 25.8%

So which one is correct 25% or 6%?

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