<div style="padding:40px;color:#cbccc6"><h1>导数=切线斜率</h1><p>割线 → 切线。h→0。</p><div style="padding:20px;background:#0d1017;border-left:3px solid #ffb454"><span class="katex-error" title="ParseError: KaTeX parse error: Unexpected character: '\' at position 2: f\̲" style="color:#cc0000">f\</span></div><p style="color:#707a8c">该页面需要 JavaScript 进行交互式可视化。</p></div>