\begin{equation}
Y(z) = H(z)H(z^{-1})X(z) = (h(1)+h(2)+ ...+ h(n+1)z^{-n})(h(1)+h(2)+ ...+ h(n+1)z^{n})X(z)
\end{equation}
我这样写了等式。但我想得到第二个等式后的底线。我该怎么做?
答案1
请尝试以下操作:
\usepackage{mathtools}
\begin{document}
%%If you need the equation number center to both of the equations
\begin{equation}
\begin{split}
Y(z) &= H(z)H(z^{-1})X(z)\\
&= (h(1)+h(2)+\cdots+ h(n+1)z^{-n})(h(1)+h(2)+\cdots+ h(n+1)z^{n})X(z)
\end{split}
\end{equation}
%%If you need the equation number second line of the equations
\begin{align}
Y(z) &= H(z)H(z^{-1})X(z)\nonumber\\
&= (h(1)+h(2)+\cdots+ h(n+1)z^{-n})(h(1)+h(2)+\cdots+ h(n+1)z^{n})X(z)
\end{align}
\end{document}