alleryPoint of inflection of curve y = f(x) is where:
AAlways at origin
Bf'' = 0 and changes sign (concavity changes)
Cf = 0
Df' = 0
Answer & Solution
Correct answer: B. f'' = 0 and changes sign (concavity changes)
**Inflection point:** where f''(x) changes sign (concave up ↔ concave down).
**Necessary condition:** f''(x) = 0 (or undefined).
**Sufficient:** sign change of f''.
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