Negative feedback (-ve fb) is just connecting the Vout back to V-(inverted input). This voltage can be returned to V- through a resistor, capacitor, just only wire or some complex circuit.
It also make use of the same open gain formula of Vout = Ao(V+ – V-). Since it is a -ve fb, V- will be function/part of Vout (fVout). Therefore formula becomes Vout = Ao(V+ – fVout).
There 2 types of -ve fb as shown below: