帶有自訂標籤的枚舉列表，包含對齊的數學方程

Question

我該怎麼寫4°？當我使用align*或任何其他環境時，方程式會居中，我希望所有方程式都像圖片上一樣排列在一條細線上。

這是我嘗試過的：

$(i)$ $\Delta^m(\Delta^n x(t))=\Delta^n(\Delta^m x(t))=\Delta^{n+m}x(t)$\\
$(ii)$ $\Delta(cx(t))=c\Delta x(t)$\\
$(iii)$ $\Delta(x(t)+y(t))=\Delta x(t)+\Delta y(t)$\\
$(iv)$ 
      \begin{align*}
      \Delta(x(t)y(t))&= y(t)\Delta x(t)+Ex(t)\Delta y(t)\\
       &= x(t)\Delta y(t)+Ey(t)\Delta x(t)\\
       &= x(t)\Delta y(t)+y(t)\Delta x(t)+\Delta x(t)\Delta y(t)
       \end{align*}\\
 $(v)$ $\Delta\left(\dfrac{x(t)}{y(t)}\right)=
       \dfrac{y(t)\Delta x(t)-      x(t)\Delta y(t)}{y(t)\cdot Ey(t)}$ 

Answer 1

我建議您載入 (a)enumitem套件來為枚舉項建立自訂環境，以及 (b) 載入套件以在第四項中amsmath使用環境。aligned

\documentclass{article}
\usepackage{amsmath,enumitem}
\newlist{myenum}{enumerate}{1}
\setlist[myenum]{label*=\upshape\arabic*\textsuperscript{o}}
\begin{document}

\begin{myenum}
\item $\Delta^m(\Delta^n x(t))=\Delta^n(\Delta^m x(t))=\Delta^{n+m}x(t)$
\item $\Delta(cx(t))=c\Delta x(t)$
\item $\Delta(x(t)+y(t))=\Delta x(t)+\Delta y(t)$
\item $\!\begin{aligned}[t]
      \Delta(x(t)y(t))&= y(t)\Delta x(t)+Ex(t)\Delta y(t)\\
       &= x(t)\Delta y(t)+Ey(t)\Delta x(t)\\
       &= x(t)\Delta y(t)+y(t)\Delta x(t)+\Delta x(t)\Delta y(t)
       \end{aligned}$
\item $\displaystyle\Delta\left(\dfrac{x(t)}{y(t)}\right)=
       \dfrac{y(t)\Delta x(t)-      x(t)\Delta y(t)}{y(t)\cdot Ey(t)}$ 
\end{myenum}
\end{document}