Write a possible exponential function in y = a · bx form that represents each situation described below.
a. Has a y‑intercept of (0, 2) and passes through the point (3, 128).
b. Passes through the points (0, 4) and (2, 1).
a. Has a y‑intercept of (0, 2) and passes through the point (3, 128).
b. Passes through the points (0, 4) and (2, 1).