幂级数

n = 0 \sum \infty = a_{0} + a_{1} x + a_{2} x^{2} + \dots + a_{n} x^{n} + \dots

a 称为幂级数的系数

更一般的 $x_{0}$ 处的幂级数

n = 0 \sum \infty = a_{0} + a_{1} (x - x_{0}) + a_{2} (x - x_{0})^{2} + \dots + a_{n} (x - x_{0})^{n} + \dots

🪴 Cyril