(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

This is not a HW question.

I was watching a lecture on youtube - http://www.youtube.com/watch?v=ke3SL_R92ys&NR=1

At 9mins into the lecture, there is a voltage divider equation.

(screen shot attached)

In the calculation of voltage at the +ve input of an op amp, the equation is

V+ = [(Vout-Vin)/(R1+R2)]R1+Vin

Why the Vin term at the end?

If you look at the feedback part as a voltage divider with 2 voltage sources, Vout at the top and Vin at the bottom. V+ would be I*R1

I = R1/(R1+R2) * (Vout-Vin)

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Voltage divider question

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