Which exponential function shows growth f(x)=2(.5)x f(x)=2(3)x f(x)=.5(.03)x f(x)=3(.8)x

For this case we have functions of the form:
 y = A * (b) ^ x
 Where,
 A: initial amount
 b: rate of change
 x: independent variable
 We have two cases:
 b <1: the function decreases
 b> 1: the function grows.
 The function that shows growth for this case is:
 f (x) = 2 (3) ^ x
 
 f (x) = 2 (3) ^ x