1. The problem asks us to identify which of the given functions is an exponential function. 2. Recall that an exponential function has the form $$y = a^x$$ where the base $$a$$ is a positive constant not equal to 1, and the variable $$x$$ is in the exponent. 3. The first function is $$y = \left(\frac{3}{4}\right)^x$$. Here, the base is $$\frac{3}{4}$$, which is a positive number less than 1, and $$x$$ is the exponent. This matches the form of an exponential function. 4. The second function is $$y = 3x^2$$. This is a quadratic function because the variable $$x$$ is raised to the power 2, and the base is the variable, not a constant raised to the variable power. 5. Therefore, the function $$y = \left(\frac{3}{4}\right)^x$$ is an exponential function, while $$y = 3x^2$$ is not. Final answer: $$y = \left(\frac{3}{4}\right)^x$$ is the exponential function.