I have this error: Paragraph ended before \align was complete. What can i do?

Question

Hello I have this code from LaTeX, but it didn't work? Any idea? I would appreciate if somebody can help me. :)

\begin{align} 
\begin{split}
  h'(v)     &= \lim_{h\to0}\frac{\sqrt{3-2(v+h)}-\sqrt{3-2v}}{h}\\
  &=\lim_{h\to0}\frac{\sqrt{3-2v-2h}-\sqrt{3-2v}}{h}\\
  &=\lim_{h\to0}\frac{(\sqrt{3-2v -2h}-\sqrt{3-2v})(\sqrt{3-2v-2h}+
   \sqrt{3-2v})}{h(\sqrt{3-2v -2h}+\sqrt{3-2v})}\\
  &=\lim_{h\to0}\frac{3-2v-2h-3+2v}{h}
  &=\lim_{h\to0}\frac{-2h}{h(\sqrt{3-2v -2h}-\sqrt{3-2v})}\\
  &=\lim_{h\to0}\frac{-2}{(\sqrt{3-2v -2h}-\sqrt{3-2v})}\\
  &=\frac{-2}{(\sqrt{3-2v -2(0)}-\sqrt{3-2v})}\\
  &=\frac{-2}{(\sqrt{3-2v}-\sqrt{3-2v})}\\
  &=\frac{-2}{(2\sqrt{3-2v}\\
  &=\frac{-1}{(\sqrt{3-2v}\\
\end{split} 
\end{align}

Here's the link of my work: https://www.writelatex.com/1561256wvkbwk

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}. — , Oct 03 '14 at 06:50
@egarro You can add it, but please complete the MWE, the snippet isn't enough. — Aradnix, Oct 03 '14 at 06:55

Astrinus · Accepted Answer · 2014-10-03T07:01:17.623

2

Last two lines:

&=\frac{-2}{(2\sqrt{3-2v}\\
&=\frac{-1}{(\sqrt{3-2v}\\

You forgot to close the \frac{}{} (and there is a useless ( ):

&=\frac{-2}{2\sqrt{3-2v}}\\
&=\frac{-1}{\sqrt{3-2v}}\\

There is also a missing \\ in the 4th line of the split environment.

Full code:

\documentclass[a4paper,10pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\begin{document}
\begin{align} 
\begin{split}
h'(v)   &= \lim_{h\to0} a\frac{\sqrt{3-2(v+h)}-\sqrt{3-2v}}{h}\\
&=\lim_{h\to0}\frac{(\sqrt{3-2v -2h}-\sqrt{3-2v})(\sqrt{3-2v -2h}+\sqrt{3-2v})}{h(\sqrt{3-2v -2h}+\sqrt{3-2v})}\\
&=\lim_{h\to0}\frac{\sqrt{3-2v -2h}-\sqrt{3-2v}}{h}\\
&=\lim_{h\to0}\frac{3-2v-2h-3+2v}{h}\\
&=\lim_{h\to0}\frac{-2h}{h(\sqrt{3-2v -2h}-\sqrt{3-2v})}\\
&=\lim_{h\to0}\frac{-2}{(\sqrt{3-2v -2h}-\sqrt{3-2v})}\\
&=\frac{-2}{(\sqrt{3-2v -2(0)}-\sqrt{3-2v})}\\
&=\frac{-2}{(\sqrt{3-2v}-\sqrt{3-2v})}\\
&=\frac{-2}{(2\sqrt{3-2v}}\\
&=\frac{-1}{(\sqrt{3-2v}}\\
\end{split} 
\end{align}
\end{document}

edited Oct 03 '14 at 07:01

answered Oct 03 '14 at 06:52

Astrinus

1,809
10
28

I fix the error with your suggestion, but now i have a new error: "Extra alignment tab has been changed to \cr.
l.121 \end{align}
– egarro Oct 03 '14 at 06:54
@egarro Have you put the missing \\ on the 4th line of the split environment? By line I mean one with &=. – Astrinus Oct 03 '14 at 06:57
Yes i did.. Now appears this: "Missing } inserted. } l.121 \end{align}" – egarro Oct 03 '14 at 06:59
The code compiles fine for me. I'll edit the answer to show the full code. – Astrinus Oct 03 '14 at 07:00
Also does on writeLaTeX. – Astrinus Oct 03 '14 at 07:05
Thank you so much! Do you know how can i put a picture in the first page? – egarro Oct 03 '14 at 07:15
@egarro What do you mean? \includegraphics wouldn't suffice? – Astrinus Oct 03 '14 at 07:19
I did it but if you can see the picture that i add doesn't appear on the first page... – egarro Oct 03 '14 at 07:19
@egarro I would suggest to open a new question for the figure question. Do you need it on a titlepage? – Johannes_B Oct 03 '14 at 07:20
Maybe on writeLaTeX the image is not uploaded. Have you tried it on your PC? – Astrinus Oct 03 '14 at 07:22
Yes i do... Can you help me with that? I think that is very simple for a new question. :) – egarro Oct 03 '14 at 07:22
1

your titlepage ends at the end of the document. That is shouldn't be. Also, there are many wrong things coming to my eye. Have your read some basic material on mathematical typesetting? I stongly advice you to do. – Johannes_B Oct 03 '14 at 07:22
I really don't actually it is the first time that i use this tool, the problem is that i need finish this job as soon as possible. – egarro Oct 03 '14 at 07:24
@egarro The image does appear, but on the next page! Try \includegraphics[width=0.2\textwidth]{deTemplate.png}\\[1cm] and pay attention to @Johannes_B . – Astrinus Oct 03 '14 at 07:25
@egarro You should not \end{document} at the beginning of it! I've corrected some of your errors. – Astrinus Oct 03 '14 at 07:27
@Astrinus, Thank you for your help, but theres a lines in my work, what happend? – egarro Oct 03 '14 at 07:32
Where? On the third page? You have written outside of the align environment. – Astrinus Oct 03 '14 at 07:34
No, theres a lines on all pages, are like rectangles and squares.. – egarro Oct 03 '14 at 07:36
1

What are you expecting \usepackage{showframe} would do? – Astrinus Oct 03 '14 at 07:37
I remove them. ;) – egarro Oct 03 '14 at 07:37
@Astrinus Thank you again for all your help, i am very grateful. – egarro Oct 03 '14 at 07:40
@Astrinus @egarro I put showframe there. It shows you the printable type area as well as some other stuff (header, footer, marginpar). I wasn't aware that it is that interactive. – Johannes_B Oct 03 '14 at 07:51
@Johannes_B Can you remove the title "attention"? I need to finish this work, and i really appreciated your help but please don't write things my work. ;) – egarro Oct 03 '14 at 07:58
1

You read it, thats all i wanted, you can remove it yourself. Just make sure the operators look nice ;-) – Johannes_B Oct 03 '14 at 08:00

I have this error: Paragraph ended before \align was complete. What can i do?

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