2020-01-05 テーラー級数 [ \begin{align} f(x) = & f(x_1)+f'(x_1)(x-x_1)+\frac{1}{2!}f''(x_1)(x-x_1)2 + \cdots \ & +\frac{1}{n!}f^{(n)}(x_1)(x-x_1)n+ \cdots \tag{3} \end{align} ]