Consider the function f(x) = 7x + 8x ^-1. For this function there are four important intervals: (-\infty, A], [A,B),(B,C), and [C,\infty) where A, and C are the critical numbers and the function is not defined at B.
For each of the following intervals, tell whether f(x) is increasing or decreasing.
(i infty, A]:
Any help will be appreciated!