I need help on the theory behind the voltages on an op-amps negative and positive terminal. Why does the positive and negative terminals must have equal voltages?

opamps infinite gain is one of the ideal characterestics of op-amps.(so that it can amplify even the very weak signal.) As the basic building block of opamp is differential amplifier, it amplifies the difference b/w the signals applied at the two terminals. so.. the gain would be.. gain=v(out)/ v(id)=infinity where v(out) is o/p voltage and v(id) is voltage difference b/w two terminals . for the gain tobe infinite.. denominator should be zero..i.e., the difference b/w two terminal voltages should be zero..that's why the voltages at two terminals must be equal.. while treating for ideal case. v(id)=V1-V2 vid=0=> V1=V2

Two voltage power supplies having negative outputs with respect to common are combined to give positive as well as negative output with respect to common base . An operational preamplifier is always used as an inverter. The combination includes provision for programming by means of a voltage returned to common making the system compatible with Conventional remote control systems.