Concavity Calculator
Analyze the concavity of mathematical functions and find inflection points. Our calculator uses the second derivative test to determine where functions are concave up, concave down, and identify inflection points.
Last updated: December 15, 2024
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Supported: polynomials (x², x³, x⁴), trigonometric (sin(x), cos(x)), exponential (eˣ), logarithmic (ln(x))
Concavity Analysis
Second Derivative:
f''(x) = 6x
Concavity at x = 1:
Concave Up
Inflection Points:
x = 0
Analysis:
At x = 1, the second derivative is 6.00
Concavity Rules:
- • f''(x) > 0 → Function is concave up (∪)
- • f''(x) < 0 → Function is concave down (∩)
- • f''(x) = 0 → Possible inflection point
- • Inflection points occur where concavity changes
Quick Example Result
For function f(x) = x³ at x = 1:
f''(x) = 6x → Concave Up
Inflection point at x = 0
How This Calculator Works
Our concavity calculator analyzes mathematical functions using the second derivative test to determine the curvature direction. The calculation applies fundamental calculus principles to identify where functions curve upward or downward and locate inflection points.
The Mathematical Principle
f''(x) > 0 → Concave Up (∪)
f''(x) < 0 → Concave Down (∩)
f''(x) = 0 → Possible Inflection Point
This fundamental test determines concavity by analyzing the sign of the second derivative. When the second derivative changes sign, an inflection point occurs where the curve changes direction.
Shows concave up (∪) and concave down (∩) curve behaviors
Mathematical Foundation
Concavity analysis is based on the second derivative test from differential calculus. The second derivative measures the rate of change of the slope, indicating whether the function curves upward (positive acceleration) or downward (negative acceleration) at any given point.
- Positive second derivative indicates the slope is increasing (concave up)
- Negative second derivative indicates the slope is decreasing (concave down)
- Zero second derivative with sign change indicates an inflection point
- Concavity helps identify local maxima and minima using the second derivative test
Sources & References
- Calculus: Early Transcendentals - James Stewart (9th Edition)Standard reference for concavity and inflection point analysis
- Mathematical Association of America - Calculus Teaching GuidelinesEducational standards for teaching concavity concepts
- MIT OpenCourseWare - Single Variable Calculus ResourcesAcademic materials on second derivative applications
Need help with other calculus calculations? Check out our end behavior calculator and free fall calculator.
Get Custom Calculator for Your PlatformExample Analysis
Given Function:
- f(x): x³
- f'(x): 3x²
- f''(x): 6x
Analysis Steps:
- Find second derivative: f''(x) = 6x
- Test sign: 6x > 0 when x > 0
- 6x < 0 when x < 0
- Inflection point: x = 0 (where f''(x) = 0)
Result: Concave down for x < 0, concave up for x > 0
Inflection point at (0, 0) where concavity changes from down to up.
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