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2.4 Geometrical Application of Calculus. Concavity. The second derivative gives us information about the curves shape. f’’(x) > 0 - curve is concave upward. f’’(x) < 0 - curve is concave downward. 2.4 Geometrical Application of Calculus. Inflection.
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2.4 Geometrical Application of Calculus Concavity The second derivative gives us information about the curves shape. f’’(x) > 0 - curve is concave upward. f’’(x) < 0 - curve is concave downward.
2.4 Geometrical Application of Calculus Inflection The second derivative gives us information about the curves shape. f’’(x) = 0 - point of horizontal inflection.
2.4 Geometrical Application of Calculus Exploring Stationary Points. Yes, points of inflection as concavity does change. f’’(x) - / 0 / + + / 0 / - No points of inflection as concavity does not change. f’’(x) + / 0 / + - / 0 / -
2.4 Geometrical Application of Calculus Exploring stationary points. 1. Does the curve y = x4 have a point of inflection? Stationary point when 12x2 = 0 f(x) = x4 f’(x) = 4x3 i.e. x = 0 f(0) = 0 Stationary point @ (0, 0) f’’(x) = 12x2 Test Concavity x -1 0 1 f’’(x) +12 0 +12 Concavity does not change - Not Inflection point.
2.4 Geometrical Application of Calculus Exploring stationary points. 2. Does the curve y = x3 have a point of inflection? Stationary point when 6x = 0 f(x) = x3 f’(x) = 3x2 i.e. x = 0 f(0) = 0 Stationary point @ (0, 0) f’’(x) = 6x Test Concavity x -1 0 1 f’’(x) -6 0 +6 Concavity does change - Inflection point.