2.55 Derive an expression for the gain of the voltage follower of Fig. 2.14, assuming the op amp to be ideal except for having a finite gain A. Calculate the value of the closed-loop gain for A = 60 dB, 40 dB, and 20 dB. In each case find the percentage error in gain magnitude from the nominal value of unity. ; 0.999, −0.1%; 0.990, −1%; 0.909, −9.1%