For f (x) = 2x - x2 + 1, describe the concavity of f (x). o f(x) is concave down for X and has no concavity at x = of (x) is concave up for X > and has no concavity at X = O - o f (x) is concave down for X 6 and has no concavity at X = o f(x) is concave up for X and has no concavity at X =