Final answer:
A stellar-mass black hole can be located in a binary system with a companion star, a star cluster, or interstellar space, whereas a supermassive black hole is found at the center of a galaxy.
Step-by-step explanation:
A stellar-mass black hole can be located in various environments within a galaxy. While a supermassive black hole is typically found at the center of a galaxy, a stellar-mass black hole may exist in a binary system with a companion star, in a star cluster, or wandering in interstellar space. Furthermore, observational evidence for stellar-mass black holes often arises from binary star systems. Here, the invisible star emits flickering X-ray emission from an accretion disk indicating its presence, and the mass calculated for the invisible object is typically greater than 3 solar masses (Msun), which exceeds the expected mass for a neutron star, thus suggesting it to be a black hole.