Definition 13.13 High School Mathematics · 第 13 章 — Sequences: A First Course A sequence (un)(u_n)(un) is increasing if un+1≥unu_{n+1} \geq u_nun+1≥un for all nnn, and decreasing if un+1≤unu_{n+1} \leq u_nun+1≤un for all nnn. 在原文中阅读 →