Applications of Derivatives · Curve Analysis

Concavity

f(x)>0concave up;f(x)<0concave downf''(x) > 0 \Rightarrow \text{concave up}; \quad f''(x) < 0 \Rightarrow \text{concave down}

The second derivative determines concavity. Concave up means the curve opens upward (bowl shape). Concave down means it opens downward.

  • 0 variables
  • 2 worked examples
  • 15 in Applications of Derivatives

Worked examples

Determine the concavity of f(x) = x³ on (-∞, 0) and (0, ∞).
  1. f''(x) = 6x
  2. x < 0: f''(x) < 0 → concave down
  3. x > 0: f''(x) > 0 → concave up

Answer: Concave down on (-∞, 0), concave up on (0, ∞).

1 more worked examplePremium

Find where f(x) = x⁴ - 6x² is concave up and concave down.

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