I asked the professor and he hinted that I should use a KCL loop at the inputs with virtual ground. But I still don't fully understand it myself.
How would I go about this circuit? Thanks guys!

 

Is that negative resistance?

 

No it's just a dash. Values are 91k and 51k

 

Ok.
Can you follow the current from V1 and to the ground? Call this current A. Can you write out which components it goes through? What the voltage would be across that component?

 

Yep

Ok.
Can you follow the current from V1 and to the ground? Call this current A. Can you write out which components it goes through? What the voltage would be across that component?

Yep

 

Yep

Yep

Write it out. I want to see an equation.

 

Would current A be going through R1 and R2. I don't know what the voltage that would be

 

Would current A be going through R1 and R2. I don't know what the voltage that would be

Almost correct. It will go through R1, R2 and Rgen1.

So you are looking at something like this:
A*R1+A*R2+A*Rgen1-V1=0
A*R1+A*R2+A*Rgen1=V1
A*(R1+R2+Rgen1)=V1
A*(91+91+51)=V1
233A=V1

Now do the same for the V2. Some current is leaving V2, call it current B, follow its path. Also you might want to redraw the "V2 circuit". Instead of Vout being a dot in space, replace it with a circle like the other independent voltage sources.

 

So then BR4+BR3+BRgen2=V2 and since its a difference amplifier do I subtract the voltages?

 

So then BR4+BR3+BRgen2=V2 and since its a difference amplifier do I subtract the voltages?

Vout is connected to R4... It is part of this circuit.

 

Oh woops! so BR4+BR3+BRgen2+V2=vout

 

What assumptions are you making about the op-amp? Are you assuming it is ideal? Even though it is stated that it's a 741?

Part (b) talks about "both circuits" -- what "both"?

 

Oh woops! so BR4+BR3+BRgen2+V2=vout

That is good. So.
Vout=B*R4+B*R3+B*Rgen2+V2
Vout=B*(R4+R3+Rgen2)+V2
Vout=B*(91+91+51)+V2
Vout=233B+V2

Now. Tell me about the "virtual ground" junctions. What do we know about those junctions? The junctions that I am talking about are:
- Junctions of R1 and R2 and OA1 positive input
- Junction of R3 and R4 and OA1 negative input
What do we know about these junctions?

 

Well it's asking for vout in term of V1 and V2 and I'm assuming that its a difference amplifier. I'm guessing there was 2 circuits to the problem but he removed one

 

But what you get for Vout in terms of V1 and V2 depends on what you assume about the opamp. In particular for this circuit, are you taking into account the input bias current or not?