Final answer:
The incorrect statement is that a function is the communicative purpose for speaking, as in mathematics, a function represents a relationship between values and an exponent denotes the power to which a base number is raised.
Step-by-step explanation:
The statement 'A function is the communicative purpose we have for speaking' is incorrect when discussing functions and exponents in the context of mathematics. In mathematics, a function describes a special relationship between values, where each input is related to exactly one output. On the other hand, an exponent refers to the number of times a base is multiplied by itself, as demonstrated by 52 which equals 25. The correct context for understanding functions and exponents is through their mathematical definitions and rules, not through their linguistics or language use parallels.