15 help with this multiple choice please

points) A linear approximation will always underestimate the value of a function nearby points if the function is O increasing O decreasing O concave up O concave down (10 points) True or False: X -2 (a) If lim f(x) = 0 and lim g(x) = co then lim (f(x) - g(x)) = 0 O True O False (b) There exists a function f such that f(x) 0, and f"(x)