选择对齐方程的对齐点？

Question

所以我有几个方程式，我想根据一些字母来对齐\align*：

目前结果：

                    a) numbers + numbers = biggernumber
        b) morenumbers + morenumbers = muchbiggernumber
c) evenmorenumbers + evenmorenumbers = evenbiggernumber
                            d) etc. + etc. = etc.number

想要的结果：

a) numbers + numbers = biggernumber
b) morenumbers + morenumbers = muchbiggernumber
c) evenmorenumbers + evenmorenumbers = evenbiggernumber
d) etc. + etc. = etc.number

或者：

a) numbers         +     numbers     =     biggernumber
b) morenumbers     +   morenumbers   = muchbiggernumber
c) evenmorenumbers + evenmorenumbers = evenbiggernumber
d) etc.            +       etc.      =       etc.number

Answer 1

您需要使用&来设置对齐位置。下面首先是没有对齐的原始情况，然后是您想要的第一个对齐位置a)，b)等等。第二个想要的替代方案最好使用数组来完成。我还提供了一个我认为更易于阅读的版本。

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
  a)\ \text{numbers} + \text{numbers} = \text{bigger number}\\
  b)\ \text{more numbers} + \text{more numbers} = \text{much bigger number}\\
  c)\ \text{even more numbers} + \text{even more numbers} = \text{even bigger number}\\
  d)\ \text{etc.} + \text{etc.} = \text{etc. number}
\end{align*}

\begin{align*}
  a)\ & \text{numbers} + \text{numbers} = \text{bigger number}\\
  b)\ & \text{more numbers} + \text{more numbers} = \text{much bigger number}\\
  c)\ & \text{even more numbers} + \text{even more numbers} = \text{even bigger number}\\
  d)\ & \text{etc.} + \text{etc.} = \text{etc. number}
\end{align*}

\begin{displaymath}
  \begin{array}{ll@{}c@{}c@{}c@{}r}
    a) & \text{numbers} &{}+{}& \text{numbers} &{}={}& \text{bigger number}\\
    b) & \text{more numbers} &{}+{}& \text{more numbers} &{}={}& \text{much bigger number}\\
    c) & \text{even more numbers} &{}+{}& \text{even more numbers} &{}={}& \text{even bigger number}\\
    d) & \text{etc.} &{}+{}& \text{etc.} &{}={}& \text{etc. number}
  \end{array}
\end{displaymath}

\begin{align*}
  a) && \text{numbers} + \text{numbers} &= \text{bigger number}\\
  b) && \text{more numbers} + \text{more numbers} &= \text{much bigger number}\\
  c) && \text{even more numbers} + \text{even more numbers} &= \text{even bigger number}\\
  d) && \text{etc.} + \text{etc.} &= \text{etc. number}
\end{align*}
\end{document}