Please need an answer

Consider the function f(a) = 2 - 5x2 on the interval [-1, 6). Find the average rate of change of the function on this interval, i.e. f(6) - f(-1) -10x - 5 6 - (-1) By the Mean Value Theorem, we know there exists a c in the open interval (-1, 6) such that f' (c) is equal to this average rate of change. For this problem, there is only one c that works. Find this value of c. C =