# Ok how do they got this ?

1. Jun 14, 2013

### k31453

1. The problem statement, all variables and given/known data
I am following book and they got this equation but i dont know how they got it ??
[Broken]

2. Relevant equations

3. The attempt at a solution
I know they use kirchoff's voltage law but at which point they are choosing and how they are going and acquire this equation.?

Last edited by a moderator: May 6, 2017
2. Jun 15, 2013

### Simon Bridge

You don't apply the voltage law at a point - you apply it to a loop.
They tell you which loop they applied it to - the one containing R4 and R3.

Redraw the circuit diagram so the loop containing R4 and R3 looks like a loop and do the mesh analysis - don't forget to appropriately model the op-amp.

3. Jun 15, 2013

### Chopin

Hint: Remember that all ground symbols are connected to each other.

4. Jun 17, 2013

### CWatters

I find it helps by writing a KVL sum so it adds to zero. Then rearrage it. Don't start by writing "Vo = "