Consider the function f(3) = 2x + 7x^-1 . For this function there are four important intervals:(-?, A], [A, B),(B,C], and [C,?) 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(x) is increasing or decreasing.(-?, A): __________(A, B): __________(B,C): __________(C,?): ___________Note that this function has no inflection points, but we can still consider its concavity. For each of the following intervals, tell whether f(x) is concave up or concave down.(-?, B): ____________(B,?): ____________