Answer:
Exponential functions:
,
and 
Non-exponential functions:
,
and 
Step-by-step explanation:
The general form of an exponential function is

where, a is initial value and b is growth factor.
It means the variable term i.e., x must be the exponent . In other words we can say that the variable term must be in the power of constant terms.
We need to check whether the given function is an exponential function or not.
The given function is

It is an exponential function with initial value 8 and growth factor e≈2.718.
Similarly,
and
are exponential functions.
,
and
are non-exponential functions.