1. The problem statement, all variables and given/known data Find resistance R so that maximum power is transferred to this resistor. http://i.imgur.com/XsxTFCq.png 2. Relevant equations Rth = Voc/Isc 3. The attempt at a solution I tried to find the Thevenin equivalent circuit across the resistor R because the Thevenin resistance must be equal to the load resistor in order for maximum power to be transferred. I replaced R with an open circuit to find the open circuit voltage. Using Nodal Analysis, I obtained the equation: (V1 - 4V)/5 + V1/15 = 0 So, V1 = 3 = Voc. Then I redrew the circuit and replaced R with a short circuit and solved for two voltages at the nodes. http://i.imgur.com/247x27x.png I used Nodal Analysis and obtained two equations. [3Vx = V2/6] (V1-4V)/5 + V1/15 + V2/2 + (V1-V2)/5 = 0 V2/6 + (V2-V1)/5 = 3V2/6 I got V1 = 48V, V2 = -72V and Isc = V2/6 = -12A so I got Rth = 3/-12 = -0.25 ohms. This isn't right, but I"m not sure what I did wrong.