Hello friends, I'm kinda stuck in the following problem. This is related to the derivative and possibly with the concept of maxima and minima. I've this assignment due on tuesday, and I am not getting any idea although trying it since two days before. can anybody help me, please? For the cubic f(x) = ax3 + bx2 + cx + d, a ≠ 0, Find conditions on a, b, c, and d to ensure that f is always increasing or always decreasing on (-∞,+∞).