The function f(x) is said to concave down in an interval [a, b], if = _____?
- f''(x) < 0
- f'(x) < 0
- f''(x) > 0
- None of these
Explanation
A function is concave down on an interval if its second derivative is negative over that interval.
Graphically, this means the curve bends downward like an upside-down bowl.