> For the complete documentation index, see [llms.txt](https://overleaf-pro.ayaka.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://overleaf-pro.ayaka.space/latex/zh-tw/latex-cuo-wu/02-command-r-invalid-in-math-mode-on-input-line-xxx.md).

# 在第 XXX 行輸入中，數學模式下的指令 \r 無效

當在數學模式中不正確地使用特殊字元時，就會出現此錯誤。在 LaTeX 中，某些字元，例如帶重音符號的字母，或帶變音符號的字母，不能寫在數學模式中。解決這個問題的最佳方法是將它們寫在 **`\text{...}`** 由 **`amsmath`** 套件。

## 常見原因

**在數學模式中包含帶重音符號、變音符號等的字母：**

例如，ö 其實是 {\\"o}

**在數學模式中使用特殊符號：**

例如，angstrom \AA 其實是 \r{A}


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