Please explain why, label any formulas used, thanks!

Do not use technology. The figure below shows the graph of f', the derivative of f. The function f is a twice differentiable function on x E (-co, co), f"(-0.8) = 0, and f"(1.3) = 0. X -3 -2 (a) For what values of x is f increasing? (Enter your answer using interval notation.) (0,2) (b) For what values of x is the graph of f concave downward? (Enter your answer using interval notation.) (-2, -.8), (1.3,00) (c) Is F(-0.4) - f(0) -0.4 - 0 positive or negative? positive negative