[Tex/LaTex] Aligned equations in LaTeX

alignequationsline-breaking

I have a long equation in LaTeX, which I need to break up into more lines. I've done this, although its not quite what I was looking for. Here is a MWE showing my problem:

\documentclass[10pt]{article}

\usepackage[T1]{fontenc}
\usepackage{amsmath, amsthm, amssymb}
\usepackage[ansinew]{inputenc}

\begin{document}
\begin{equation}
  \begin{aligned}
        \alpha &= 1 &&+ 2     \\
               &    &&- 3 + 4 \\
               &= 4 \\
               &=5-1,
  \end{aligned}
\end{equation}
\end{document}

So there is a long equation broken into 2 lines, followed by 2 short lines. Here is what I desire:

  1. There should be an equation label for each equality sign, so 3 in total. At the moment there is only one

  2. The "+2" and "-3+4"-parts are aligned right, which distorts the whole equation. I'm not quite sure why it is doing that, I haven't told it explicitly to do so.

Is there a way to correct these errors?

EDIT: Original output looks like

Original output

Best Answer

Instead of aligned, I would suggest an align environment; \notag can be used to suppress the tag for selected lines; the alignment for the second line can be produced with the help of a \phantom:

\documentclass[10pt]{article}
\usepackage[T1]{fontenc}
\usepackage{amsmath, amsthm, amssymb}
\usepackage[ansinew]{inputenc}

\begin{document}
\begin{align}
\alpha &= 1 + 2     \\
&\phantom{{}=1}-3 + 4 \notag\\
&= 4 \\
&=5-1,
\end{align}

\end{document}

enter image description here

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