The expo function y = 2 ^ x has the following properties:
1. The domain is the set of all real numbers.
2. The range is (0, infinity).
3. The graph appears in Quadrants I and II and never touches the x-axis.
4. The function is always positive.
5. The inverse function of y = 2 ^ x is found b)y interchanging x and y here
and solving x = 2^y for y: Taking the ln of both sides, ln x = y ln 2, so that
y = (ln x) / (ln 2) (ONLY for positive x)
