I have a problem regarding homework, its about nodeanalysis in a circuit involving OP amp, I dont really understand how to deal with the OP amp part...

 

Start out by writing KCL equations for nodes 2 and 5. Let the voltages at your nodes be V1 at node 1, V2 at node 2, etc.

The equation at node would be:

(V2-V1)/2000 + (V2-V3)/3000 = 0

Later, you can set V1 = 1 volt and V3 = 2 volts.

Try you hand at writing an equation for node 5.

 

I dont understand how calculate with the ideal OP amp, it should be infinite impedance from output and zero impedance from input i think, but in calculations how do it be?

 

The infinite impedance at the inputs means you don't have to allow for any current into those terminals.

Look at the equation I gave you in post #2; there is no term for current into the opamp inputs.

Just write a similar equation for node 5. Do you know how to use the nodal method of circuit analysis?

You need 3 equations in 3 unknowns. Your unknowns are V3, V4 and V5. V1 and V3 are known.

Your 3rd equation will be: V2 = V5.

So, try to write an equation for node 5.