Okay.

So, the fist quiz was how many unknown node voltages do you need?

Well, this particular case, we've got, I'm going to pick this to be my ground node.

So, that's 0, that's known, this is going to be 15, and

so, this would be V sub 1, right here, I'll call that V sub 1.

And if that's V sub 1, I'm going to call this V sub 2.

And that's everything over here.

So I need to find 2 nodes, there's 2 unknown node voltages.

And then find the KCL at the V1 node.

Okay, so I'm going to define my currents going here.

And again I'm ignoring this I sub 1, even though I want to ultimately solve for it.

I want to solve for right now, the current is leaving this node right there.

And it's gotta be all in terms of V1 or V2.

So I've got V1 all over 4K.

That's the current going this way.

The current going in this director is V1- 15

over 1K + the current going in that direction is

V1- V2 over 1K = 0.

I've got three branches leaving; I've accounted for three terms.

I've got two equations.

I would need to have another equation