Verify that the following function is a probability mass function, and determine the requested probabilities.
fx = (8/7(1/2)x
x = 0, 1, 2, ...
A. P(X = 2).
B. P(X ≤ 2).
C. P(X > 2).
D. P(X ≥ 1).
Is the function a probability mass function?