Csdrhrt

I am trying to write different equations aligned on the left (that's ok) and which go back to the line after the = sign. Also, I do not want any numeration of the equation: that's why there is a *.

documentclass{article}



usepackage{amsmath}



begin{document}



begin{flalign*}

4 &= 2 + 2\nonumber

A &= B + C + D + E + F + G + H + I + J + K + L + M + N + O + P + Q + R + S + T + U + W + X + Y + Z  \nonumber

6 &= 3 + 3&&

end{flalign*}



end{document}

As you can imagine the long equation will not fit in one line. The problem is that in my case it continues even after the end of the page and I do not see the end. As you can see:

Does someone know how to force it to go to the line, after the = sign of the previous line ?

Is it one of these you want?

documentclass{article}

usepackage{mathtoolsh}

usepackage{showframe}

renewcommand{ShowFrameLinethickness}{0.3pt}



begin{document}



begin{flalign*}

4 &= 2 + 2&&\

A &= begin{multlined}[t]B + C + D + E + F + G + H + I + J + K+ L \+ M + N + O + P + Q + R + S + T + U + W

end{multlined} \

6 &= 3 + 3 

end{flalign*}

vskip1cm



 begin{flalign*}

4 &= 2 + 2&&\

A &=B + C + D + E + F + G + H + I + J + K+ L \

  & + M + N + O + P + Q + R + S + T + U + W \

6 &= 3 + 3

end{flalign*}



end{document}     

Here's a solution that uses a parbox for the material to the right of the = symbol in the 2nd equation. An advantage of this approach is that it allows automatic line breaking.

The macro mybox takes two arguments: the first, optional, argument gives the width of the box (0.9textwidth by default); the second, mandatory, argument gives the material to be placed (in displaystyle math mode) in the "box". If you wanted to make the box occupy, say, a width of 0.93textwidth, you'd simply write mybox[0.93]{B + C + ... + Z}.

documentclass{article} 

usepackage{amsmath} 

% default width of parbox = 0.9textwidth

newcommandmybox[2][0.9]{parbox[t]{#1textwidth}{$displaystyle #2$}}

begin{document}

hrule % just to illustrate width of text block

begin{align*} % no need for 'flalign*' env.

4 &= 2 + 2\

A &= mybox{B + C + D + E + F + G + H + I + J + K + L + M + 

            N + O + P + Q + R + S + T + U + W + X + Y + Z}\

6 &= 3 + 3

end{align*}

end{document}

You can pass the fleqn option to amsmath to left align all your equations automatically. Also, I would align the + sign after the = sign above using the align* environment.

documentclass{article}

usepackage[fleqn]{amsmath}

begin{document}



begin{align*}

4 &= 2 + 2\

A &= B + C + D + E + F + G + H + I + J + K+ L \

  &phantom{{}=} + M + N + O + P + Q + R + S + T + U + W \

6 &= 3 + 3

end{align*}



end{document}