Step 1: \ \
\Find the thevinins equivalent resistance.
\1.Open the load resistor.
\2.Open Current Sources and Short Voltage Sources.
\3.Calculate the Open Circuit Resistance. This is the Thevenin Resistance (RTH).
\Redraw the circuit :
\4 ohm resistor does not involved in the circuit since it is opend.
\So the equivalent resistance will be .
Solution : \ \
\Thevenin Resistance is .
\
\
\
Step 1: \ \
\Find the thevinins equivalent resistance.
\1.Open the load resistor.
\2.Calculate the Open Circuit Voltage. This is the Thevenin Voltage (VTH).
\Redraw the circuit :
\Loop current for the above network is 1 A.
\The voltage across the resistor R2 is :
\The Thevenin Voltage will be voltage across R2.
\Thevenin Voltage is .
Solution : \ \
\\
Thevenin Voltage is .