泰勒展开证明e是无理数

自然常数e为数学中一个常数,其值约为2.718281828459045...

要证明e是无理数,可以用反证法来证明e不是有理数

假设 e 是有理数,即存在整数 和 q q( q

The Taylor series for a function ( f(x) ) around a point ( a ) is given by:

[f(x)=f(a)+f(a)(xa)+f(a)2!(xa)2+f(a)3!(xa)3+][ f(x) = f(a) + f'(a)(x-a) + \frac{f''(a)}{2!}(x-a)^2 + \frac{f'''(a)}{3!}(x-a)^3 + \cdots ]

For the exponential function ( e^x ), the Taylor series expansion centered at 0 is:

[ex=1+x+x22!+x33!+x44!+=n=0xnn!][ e^x = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \frac{x^4}{4!} + \cdots = \sum_{n=0}^{\infty} \frac{x^n}{n!} ]

f(x)=xe2piiξxf(x) = x * e^{2 pi i \xi x}

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