1. The problem statement, all variables and given/known data We got the following circuit: http://tinypic.com/view.php?pic=1zl7xg2&s=6 u_in is input u_ut is output 3. The attempt at a solution I assumed that the upper amp has voltage u_in on the positive terminal. And that the lower amp has voltage 0 V on the positive terminal. then i calculated u_ut but the ratio then becomes: u_in/u_ut = 0 Because the current from the upper amplifiers output terminal to the output terminal u_ut is i=u_in/2R which then gives us u_ut=u_in -(i*2R) = u_in -u_in the right answer should be -1 :'( help please.