Find 
using superposition rule:
The superposition theorem states that the response (voltage or current) in any branch of a linear circuit which has more than one independent source equals the algebraic sum of the responses caused by each independent source acting alone, while all other independent sources are turned off (made zero).
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Use Thévenin’s theorem to determine 
.
Solution
Lets break the circuit at the 
load as shown in Fig. (1-27-2).
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Determine 
, 
and 
using the superposition method.
Solution
I. Contribution of the 
voltage source:
We need to turn off the current source by replacing it with an open circuit. Recall that we do not turn off dependent sources. The resulting circuit is shown below.
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Determine 
and 
using the superposition method.
Solution
I. Contribution of the 
voltage source:
To find the contribution of the voltage source, other three sources should be turned off. The 
voltage source should be replaced by short circuit. The current source should be replaced with open circuits, as shown below.
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