I've the following problem:

http://s9.postimg.org/6wgvejisv/Untitled.png

I've assumed that that the node between 4 ohms resistor, 3 ohms resistor and 9 Volts source, and the node between 9 Volts source, 2 ohms resistors and 6 ohms resistor, are forming a Supernode.

So, Applying KCL on the Supernode:

\(I_{4 \Omega}=I_{3 \Omega}+I_{2 \Omega}+I_{6 \Omega}\)

\(\frac{V_{1} - 21}{4}=\frac{V_{1}}{3}+\frac{V_{2}}{2}+\frac{V_{2}}{6}\)

\(V_{1}+8V_{2}=-63 \rightarrow (1)\)

Applying KVL on the Supernode:

\(-V_{1}-9+V_{2}=0\)

\(V_{1}-V_{2}=-9 \rightarrow (2) \)

Solving (1) and (2):

V1= -63, V2=-9

Which - as you can see above - not the right answer.

Any help?