\fbox 围绕方程解导致日志错误：缺少 $ 插入

Question

堆栈社区！

无日志错误前我插入了\fbox围绕多步方程的解，没有错误。

应用\box如下：

&\fbox{\boldsymbol{x = \-3\pm 3i\sqrt{3} \qquad x=6} } \\导致这个错误：

请告诉我为什么会出现这个错误。

谢谢！下面是 mwe

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{framed} %box para
\usepackage{multicol}
\usepackage{tasks}
\usepackage{xcolor}
\usepackage[margin=0.5in]{geometry}
\usepackage{tikz}
\usetikzlibrary{shapes.callouts}

\newcommand*{\callout}[2]{\hspace{-5em}
    \tikz[baseline=(X)] \node[shape = rectangle callout, 
        fill=white, 
        draw= black, 
        minimum width=4.5em,
        rounded corners,
        callout relative pointer={(+0.55,-0.45)}, 
        font = {\sffamily},
        ] (X) {${\scriptsize\begin{matrix}\textrm{1st root/} \\ \textrm{solution}\end{matrix}}$};%
    \tikz[baseline=(X.base)] \node[rectangle, fill=yellow, inner sep=1mm] (Y) at ([yshift = -2.2em]X) {$#1$};%
    \tikz[baseline=(X.base)] \node[] at (Y.east) {$#2$};%
}

%\usepackage{bm}%bold equation
\setlength{\parindent}{0pt} % removes paragraph indentation

\pagestyle{head}
\header{Algebra II: Assignment: 10-C Solving Polynomial Equations}
       {}
       {Due 03/12/2023} 

\newcommand{\pagetop}{%
  %\makebox[\textwidth]%{Name:\enspace\hrulefill}\par
  \vspace{4mm}
  \fbox{\fbox{\parbox{\dimexpr\textwidth-4\fboxsep-4\fboxrule}{
    \textbf {Solve each polynomial equation by factoring. Find all real and/or  imaginary/complex roots. Simplify answers.}
    %\par
    %\bigskip

  }}}\par
  \vspace{0.5mm}
}
\setlength{\jot}{1em}
%define highlighting

\newcommand{\hll}[1]{\colorbox{yellow}{$\displaystyle #1$}}

\begin{document}
\pagetop

\settasks{
    after-item-skip=3em,    after-skip=2cm,
    label-width=2em,
    item-indent=3em,
    label=(\arabic*),
    column-sep=2em
}

\begin{tasks}(2)
    % Problem 1:
    \task \(
    \begin{aligned}[t]
        & x^3-216 = 0 \\
        & \hspace{2em}
        \begin{aligned}[t]
            & \sqrt[3]{x^3} = 3 \qquad \sqrt[3]{216} = 6 \\
            & \hll{(x-6)}(x^2+6x+6^2) \\[-2.2em]
            % Do not space here:        ^
            & \callout{(x-6)}{(x^2+6x+36)} \\
            & a = 1; b = 6; c = 36 \\
            & x = \frac{-(b)\pm\sqrt{(b^2)-4(a)(c)}}{2(a)} \\
            & x = \frac{-(6)\pm\sqrt{(6^2)-4(1)(36)}}{2(1)} \\
            & x = \frac{-6\pm\sqrt{-108}}{2} \\
             & x = \frac{-6\pm\sqrt{-36}\sqrt{3}}{2} \\
            & x = \frac{-6\pm 6i\sqrt{3}}{2} \\
            & x = \frac{2(-3\pm 3i\sqrt{3})}{2} \\
            &\fbox{\boldsymbol{x = \-3\pm 3i\sqrt{3} \qquad x=6} } \\
        \end{aligned}
    \end{aligned}
    \)
    % Problem #2
    \task 
    \(\begin{aligned}[t]
        & 8x^3 +125 \\
        & \hspace{2em}
        \begin{aligned}[t]
            & \sqrt[3]{8x^3} = 2x \qquad \sqrt[3]{125} = 5 \\
            & \hll{(2x+5)}(4x^2-10x+5^2) \\[-2.2em]
            & \callout{(2x+5)}{(4x^2-10x+25)} \\
            & a = 4; b = -10; c = 25 \\
            & x = \frac{-(b)\pm\sqrt{(b^2)-4(a)(c)}}{2(a)} \\
            & x = \frac{-(-10)\pm\sqrt{(-10^2)-4(4)(25)}}{2(4)} \\
            & x = \frac{10\pm\sqrt{-300}}{8} \\
            & x = \frac{10\pm 10i\sqrt{3}}{8} \\
            & x = \frac{2(5\pm 5i\sqrt{3})}{8} \\
            & x = \frac{5\pm 5i\sqrt{3})}{4} \qquad x=-\frac{-5}{2} \\
        \end{aligned}
    \end{aligned}
    \)
    % Problem 3
\end{tasks}

\end{document}```