2

I want to align some equations, but it's not aligning properly, code:

\begin{center}
\begin{align*}

a*b=&h_1k_1h_2k_2\\
=&h_1(h_2h_2^{-1})k_1h_2k_2\\
=&h_1h_2(h_2^{-1}k_1h_2)k_2\\
=&h_1h_2(h_2k_1h_2^{-1})^{-1}k_2

\end{align*} 
\end{center}

I want them lined up by the equal signs, but upon compiling that is not at all what's happening and I really wonder why. My preamble is \usepackage{amsmath, amssymb, amsfonts, mathtools}. Thanks in advance.

2
  • If you want to align by the equal signs, you need to put ampersands before them i.e., &=. Also, you don't need center environment because align centers the formula (in the default setting).
    – yudai-nkt
    Feb 22 '17 at 6:05
  • 1
    Aside/off-topic: The mathtools package loads the amsmath package automatically; thus, no need to load amsmath separately.
    – Mico
    Feb 22 '17 at 6:14
4

Three suggestions: (i) Don't encase the align* environment in a center environment; (ii) don't allow blank lines inside an align* (or other display math) environment; and (iii) write &= rather than =& if you want proper spacing around the = symbols.

The corrected code:

\begin{align*}
a*b&=h_1k_1h_2k_2\\
   &=h_1(h_2h_2^{-1})k_1h_2k_2\\
   &=h_1h_2(h_2^{-1}k_1h_2)k_2\\
   &=h_1h_2(h_2k_1h_2^{-1})^{-1}k_2
\end{align*} 
3
  • Thanks alot! That solves all, but one problem which I discovered now, namely that the text below this align is indented. I'm trying to comment i.e. use % before and right after the align, but it's still being indented. Any suggestions? Again thanks.
    – Thomas
    Feb 22 '17 at 6:10
  • 1
    @Thomas - Do you mean to say that the text below the display math environment starts with a paragraph indentation? If so, don't leave any blank lines (which generate a paragraph break) between \end{align*} and the start of the text.
    – Mico
    Feb 22 '17 at 6:12
  • 1
    Thanks again, that solved all of my problems this morning. You're a Latex hero!
    – Thomas
    Feb 22 '17 at 6:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.