The voltage gain of an inverting operational amplifier circuit with feedback resistor R_f and input resistor R_in is:
A-R_f / R_in
B-R_in / R_f
C1 + (R_f / R_in)
DR_in / R_f
Explanation
For an ideal inverting Op-Amp configuration, negative feedback establishes a virtual ground, yielding closed-loop gain A_v = -R_f / R_in.

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