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In calculus, Taylor's theorem, named after the mathematician Brook Taylor, who stated it in 1712, allows the approximation of a differentiable function near a point by a polynomial whose coefficients depend only on the derivatives of the function at that point. The precise statement is as follows: If n≥0 is an integer and f is a function which is n times continuously differentiable on the closed interval [a, x] and n+1 times differentiable on the open interval (a, x), then we have
Here, n! denotes the factorial of n, and R is a remainder term which depends on x and is small if x is close enough to a. Several expressions for R are available.
The Lagrange form of the remainder term states that there exists a number ξ between a and x such that
This exposes Taylor's theorem as a generalization of the mean value theorem. In fact, the mean value theorem is used to prove Taylor's theorem with the Lagrange remainder term.
The Cauchy form of the remainder term is
This shows the theorem to be a generalization of the fundamental theorem of calculus.
For some functions f(x), one can show that the remainder term R approaches zero as n approaches ∞; those functions can be expressed as a Taylor series in a neighborhood of the point a and are called analyticIn mathematics, an analytic function is one that is locally given by a convergent power series. Complex analysis teaches us that if a function f of one complex variable is differentiable in some open disk D centered at a point c in the complex field, then.
Taylor's theorem (with the integral formulation of the remainder term) is also valid if the function f has complexThe complex numbers are an extension of the real numbers, in which all non-constant polynomials have roots. The complex numbers contain a number , the imaginary unit with , i. is a square root of. Every complex number can be represented in the form , wher values or vectorThe fundamental concept in linear algebra is that of a vector space or linear space . This is a generalization of the set of all geometrical vectors and is used throughout modern mathematics. Formal definition A set V is a vector space over a field F (for values. Furthermore, there is a version of Taylor's theorem for functions in several variables.