Find the current (i) in the circuit of Fig. 2.116.

[v_1 = 4 \text{ V}, v_2 = 2 \text{ V}] Problem 4.12

Find the Thevenin equivalent circuit for the circuit of Fig. 4.78.

[\frac{v_2}{6} + \frac{v_2 - v_1}{4} = 0]