An exponential growth function has the form f(x) = a * b^x, where a > 0 and b > 1. This means that the base of the exponent, b, must be greater than 1 for the function to represent growth.
1. f(x) = 6(0.25)^x: Here, the base 0.25 is less than 1, so this represents exponential decay, not growth.
2. f(x) = 0.25(5.25)^x: In this function, the base 5.25 is greater than 1, which means it represents exponential growth.
3. f(x) = -4.25^x: The base 4.25 is greater than 1, but the negative sign in front indicates a reflection, not a standard growth function.
4. f(x) = (-1.25)^x: The base -1.25 is negative, and exponential functions typically have positive bases for growth or decay.
Therefore, the function f(x) = 0.25(5.25)^x is the exponential growth function.