Higher order derivative test

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In mathematics, the higher-order derivative test is used to find maxima, minima, and points of inflexion in an nth degree polynomial's curve.

[edit] The test

Let f be a differentiable function on the interval I and let c be a point on it such that

  1. f'(c)=f''(c)=f'''(c)=\cdots=f^{(n-1)}(c)=0;
  2. f(n)(c) exists and is non-zero.

Then,

  1. if n is even
    1. f^{(n)}(x)<0 \implies x=c is a point of local maximum
    2. f^{(n)}(x)>0 \implies x=c is a point of local minimum
  2. if n is odd \implies x=c is a point of inflection

[edit] See also

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