\begin{align*} 和 \end{align*} 语法问题

Question

\newpage
        \item % Question 1) 3.4.5
            \begin{enumerate}
                \item % Question (a)
                    \begin{align}
                        \textbf{u} = [4,1,-5] \\
                        \textbf{v} = [3,-1,-5]
                    \end{align}

                    \begin{align*}
                        &\textbf{u} \times \textbf{v} \\ 
                        &= [4,1,-5] \times [3,-1,-5] \\ 
                        &= 
                            \begin{vmatrix}
                                i & j & k \\
                                4 & 1 & -5 \\
                                3 & -1 & -5 \\ 
                            \end{vmatrix}
                        &= [(1)(-5) - (-5)(3), (4)(-5) - (-5)(3), (4)(-1) - (1)(3)] \\ 
                        &= [(-5) - (-15), (-20) - (-15), (-4) - (3)] \\
                        &= [-20, -5, -7] \\

                    \end{align*}


                \item % Question (b)
            \end{enumerate}
        \item % Question 2) 3.4.7

我遇到了参数失控/缺少 $ 或 } 的问题，但我无法确定问题是什么。我注意到，当我完全删除对齐时，它就可以正常工作。有人知道我的语法可能出了什么问题吗？

Answer 1

有点晚了，但它可以帮助别人......

• 你的问题已经由@leandriis 评论解决了
• @Torbjørn T. 评论中解释了什么是 MWE (最小工作示例)
• 这是 MWE 的一个例子，我们要求您提供它而不是代码片段。请参阅其中的评论！

\documentclass{article} % we need to know which document class you use
\usepackage{amsmath}    % pacake which is necessary for compilation of MWE

\begin{document}
%   \newpage            % haven't any influence on your problem, let be omitted
\begin{enumerate}       % is missing in your code fragment. Maybe it is itemize?
                        % Since it is irrelevant to your problem can be removed
    \item % Question 1) 3.4.5
        \begin{enumerate}
            \item % Question (a)
                \begin{align}
                    \textbf{u} & = [4,1,-5] \\  % corect is `mathbf{u}
                    \textbf{v} & = [3,-1,-5]    % corect is `mathbf{v}
                \end{align}
                \begin{align*}
                \textbf{u} \times \textbf{v}  % before this line you have &, 
                                              % it cause ugly 'align' formatting,
                                              % so I remove it and preserve them 
                                              % only before sign 'equal'
                    &= [4,1,-5] \times [3,-1,-5] \\
                    &=  \begin{vmatrix}
                            i & j & k   \\
                            4 & 1 & -5  \\
                            3 & -1 & -5
                        \end{vmatrix}           \\
                    &= [(1)(-5) - (-5)(3), (4)(-5) - (-5)(3), (4)(-1) - (1)(3)] \\
                    &= [(-5) - (-15), (-20) - (-15), (-4) - (3)] \\
                    &= [-20, -5, -7]    % in your fragmen here follows empy line,  now is removed
                \end{align*}

            \item % Question (b)
        \end{enumerate}
    \item % Question 2) 3.4.7
\end{enumerate} %  closing list in the first level
\end{document}        

这使：

然而，我想知道你是否在寻找这样的东西：

梅威瑟：

\documentclass{article}
\usepackage{amsmath,
            blkarray}  % new
\usepackage{enumitem}  % new
\setlist[1]{label=\bf\thesubsection.\arabic*}

\begin{document}
\section{Section}       % added, demonstrate design of document
\subsection{Subsection} % added, demonstrate design of document
    \begin{enumerate}
\item here is probably is some text/explanation of tasks
    \begin{enumerate}
        \item % Question (a)
            \begin{align}
                \mathbf{u} & = [4,1,-5] \\
                \mathbf{v} & = [3,-1,-5]
            \end{align}
            \begin{align*}
            \mathbf{u} \times \mathbf{v}
                & =[4,1,-5] \times [3,-1,-5] \\
                & = \begin{blockarray}{*{4}{>{\scriptstyle}c}}  % instead of your 'vmatrix'
                                                                % it enable to write indices outside of matrix
                        & i & j & k   \\
                    \noalign{\setcounter{BAenumi}{1}}
                        \begin{block}{>{\scriptstyle\theBAenumi}r [*{3}{>{\normalsize}c}]}
                        & 4 & 1 & -5  \\
                        & 3 & -1 & -5 \\
                        \end{block}
                    \end{blockarray}           \\
                &= [(1)(-5) - (-5)(3),\, (4)(-5) - (-5)(3),\, (4)(-1) - (1)(3)] \\
                &= [(-5) - (-15),\, (-20) - (-15),\, (-4) - (3)] \\
                &= [-20, -5, -7] \\
            \end{align*}

        \item % Question (b)
    \end{enumerate}
\item here is probably is some text/explanation of the next tasks
    \end{enumerate}
\subsection{Subsection}
    \begin{enumerate}
\item next tasks
\item
    \end{enumerate}
\end{document}

Answer 2

  \newpage
   \LARGE
    \section{ Question (1) 3.4.5}

           \subsection {Question (a)}
             \hspace{4cm}   \begin{tabular}{rc}
                    \textbf{u} =& $\left[4\;,\; 1,-5 \right] $\\
                    \textbf{v} =& $\left[3,-1,-5 \right]
                    $% Ihave used /; to get the spaing
                \end{tabular}
       \vspace{1cm}         

       \hspace{2cm}  \begin{tabular}{rc}
                    & $\textbf{u} \times \textbf{v}$ \\ 
                    =& $\left[4,1,-5\right] \times \left[[3,-1,-5\right]$ \\ 
                    &\\
                    =& \begin{tabular}{|ccc|} 
                            i & j & k \\
                            4 & 1 & -5 \\
                            3 & -1 & -5 \\ 
                        \end{tabular}
                        \end{tabular}\\

                        \vspace{1cm}

                        \begin{tabular}{rl}
                    &= $\left[[(1)(-5) - (-5)(3), (4)(-5) - (-5)(3), (4)(-1) - 
                    (1)(3)\right]$ \\ 
                    &= $\left[(-5) - (-15), (-20) - (-15), (-4) - (3)\right]$]  
                    \\
                    &= $\left[[-20, -5, -7\right]$\\

                \end{tabular}


            \subsection{  Question (b)}

          \section{ Question 2) 3.4.7}




         \end{document}

我使用了标准 latex 命令，没有使用任何软件包。我认为这就是您想要的。请随时发送您的评论/我使用了 \LARGE。您可以删除它以获取标准输出。