!Extra } 错误，或者忘记了 \right

Question

这是我的乳胶代码：

\begin{document}
\begin{align*} 
f_{Y_2}(y_2) &= \int_{\frac{1-\sqrt{2(-1+3y_2)}}{3}}^{1}\frac{1}{4\sqrt{R}} \mathrm{d}y_1 + \int_{0}^{1-\sqrt{-1+2y_2}}\frac{1}{4\sqrt{R}} \mathrm{d}y_1 \\
f_{Y_2}(y_2) &= \frac{1}{2\sqrt{3}} \left[\arcsin \left(\frac{1}{\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} \right) - \arcsin \left(  \frac{-\sqrt{2(-1+3y_2)}}{2\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} \right) + \arcsin \left(\frac{1-\frac{3}{2}\sqrt{-1+2y_2}}{\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} -  \arcsin \left(\frac{-1}{2\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} \right) \right]
\end{align*}

Answer 1

添加\right解决了问题。但是，你的等式太宽了，你需要将其拆分，因此你必须手动调整括号的大小，而不是使用\left和\right。

\documentclass{article}
\usepackage{amsmath}
\makeatletter % https://tex.stackexchange.com/a/6796/156344
\newcommand{\vast}{\bBigg@{3.5}}
\makeatother
\begin{document}
\begin{align*} 
f_{Y_2}(y_2) &= \int_{\frac{1-\sqrt{2(-1+3y_2)}}{3}}^{1}\frac{1}{4\sqrt{R}} \mathrm{d}y_1 + \int_{0}^{1-\sqrt{-1+2y_2}}\frac{1}{4\sqrt{R}} \mathrm{d}y_1 \\
f_{Y_2}(y_2) &= \frac{1}{2\sqrt{3}} \vast[\arcsin \left(\frac{1}{\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} \right) - \arcsin \left(  \frac{-\sqrt{2(-1+3y_2)}}{2\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} \right)\\
&\hphantom{={}}+ \arcsin \vast(\frac{1-\frac{3}{2}\sqrt{-1+2y_2}}{\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} -  \arcsin \left(\frac{-1}{2\sqrt{\frac{1}{4} + \frac{3}{2}(y_2-\frac{1}{2})}} \right) \vast)\vast]
\end{align*}
\end{document}