[texhax] Exempting an equation from alignment

[E. Krishnan]

On Sat, 4 Aug 2007, Soeren D. Schulze wrote:

> I need to format something like this (whitespace-formatted here):
>
>   x (x + 1) = 0
> => x_1 = 0
>       x + 1 = 0
> => x_2 = -1
>
> This is quite a stupid example, but the first and the third line are
> supposed to be aligned (equal signs below each other), whereas the
> second and the fourth line are not supposed to influence the alignment,


Will this do?

\(\setlength{\arraycolsep}{0pt}
   \begin{array}{rr@{\;}l}
                 & x(x + 1) & = 0\\
     \Rightarrow & \multicolumn{2}{l}{x_1=0}\\
                 & x+1      & = 0\\
     \Rightarrow & \multicolumn{2}{l}{x_2=-1}
   \end{array}\)


-- 
Krishnan