Is electroencephalogram a machine?

No. It is a compound machine. A compound machine is simple machines put together to make a compound machine. For example, a bike is made of gears, wheel and axles, levers, screws, and a pulley.

A compound machine is a machine that is made up of more than one simple machine. They they change the amount of force and the direction.

An answering machine is simply a machine. A robot is also a machine, but it is capable of many complicated, self directed activities that are programmed into it.

No,because it has moving parts in it and a simple machine dose not have any moving parts

An engine is a type of machine. Machine is a more general term and would include electric, mechanical or electronic devices.