Final answer:
The equation y = 9 + 3x is not an exponential function, but a linear function.
Step-by-step explanation:
Based on the given equation, y = 9 + 3x, it is not an exponential function. An exponential function is one where the independent variable, in this case, x, appears in the exponent. In this equation, x is not in the exponent, it is multiplied by a constant (3) and added to another constant (9). This equation represents a linear function, not an exponential one.