Which of the following is true about the exponential function y=2^x

The exponential function y = 2 ^ x has these properties:

A.  The domain is the set of all real numbers.

B.  The range is zero to infinity, (0, ∞).  

C.  The graph appears in Quadrants I and II and never touches the x-axis.

D.  The function is always positive.

E.  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 natural log (ln) of both sides, ln x = y ln 2, so that y = (ln x) / (ln 2)

The above (E) can only be done if x is positive.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18