# Why are these Multiline equations not rendered?

Here:

\begin{alignat}{2} x(t) & = X+v\cos \theta t \\ y(t)& =Y+c\sin \theta t-\dfrac{1}{2}gt^2 \\ \end{alignat}

MathJax doesn't renderes it and so ShareLatex.com. Is there any particular reason?

• Welcome to TeX.SX! Please help us to help you and add a minimal working example (MWE) that illustrates your problem. It will be much easier for us to reproduce your situation and find out what the issue is when we see compilable code, starting with \documentclass{...} and ending with \end{document}. You might also want to add to your question how you're including the pdfs etc. You need to remove those – Aradnix Sep 27 '14 at 21:51 • The evironment alignat doesn't needs to use double dollar signs, in the other hand, why you tagged this question as multicolumn if you don't use that package? – Aradnix Sep 27 '14 at 21:52 • I believe that MathJax doesn't recognize alignat. Use align instead. – Sigur Sep 27 '14 at 22:14 • @Sigur MathJax is supposed to know alignat, see docs.mathjax.org/en/latest/tex.html#supported-latex-commands – Torbjørn T. Sep 28 '14 at 8:49 • @UdiBehar as noted above you need to remove the – David Carlisle Sep 28 '14 at 9:09

Yes, there is a particular reason: you must remove around the alignat. While that construction works with MathJax, it's not a reason why it should work with LaTeX, where should instead never be used.

For a single numbered equation use $$...$$; for your aligned equations there is align, which is better than alignat in this case. Each environment has the version with * at the end of the name for getting no number.

Note also that the last line mustn't be terminated by \\.

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{alignat}{2}
x(t) & = X+v\cos \theta t \\
y(t)& =Y+c\sin \theta t-\dfrac{1}{2}gt^2
\end{alignat}

\begin{align}
x(t) & = X+v\cos \theta t \\
y(t)& =Y+c\sin \theta t-\dfrac{1}{2}gt^2
\end{align}

\end{document}