νεκκοιανδ

摘要： 若 \(f(x) \in C[0,\pi]\)，求证：\(\lim_{n \to \infty}\int_0^\pi f(x)|\sin nx|dx=\frac{2}{\pi}\int_0^\pi f(x)dx\) \[ \begin{aligned} \int_0^\pi f(x) |\sin n 阅读全文