[求助]在knitr生成网页中，遇到LaTex公式不能显示的问题，请问：如何解决？谢谢！
\begin{equation}
\left\{ \begin{lgathered}
\frac{\partial_Q}{\partial_a}= -2\sum(Y_i-bX_i-a)=0\\
\frac{\partial_Q}{\partial_b}= -2\sum(Y_i-bX_i-a)X_i=0
\end{lgathered} \right.
\implies \left\{ \begin{lgathered}
b= \frac{\sum(X_i-\overline{X})(Y_i-\overline{Y})}{\sum(X_i-\overline{X})^2}=\frac{Cov(X,Y)}{S_X^2} \\
a=\overline{Y}-b\overline{X}
\end{lgathered} \right.
\end{equation}
