Consider the function f(a) = 6ac + 9x . For this function there are four important intervals: ( - 09, A], [A, B), (B, C], and [C, co) where A, and C are the critical numbers and the function is not defined at B. Find A and B and C For each of the following open intervals, tell whether f(@) is increasing or decreasing. ( - 0o, A): Select an answer v (A, B): Select an answer (B, C): Select an answer (C, 0. Select an answer v Note that this function has no inflection points, but we can still consider its concavity. For each of the following intervals, tell whether f (@) is concave up or concave down. ( - oo, B): Select an answer v (B, Oo): Select an answer v