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Best way to create an system of equations enviroment?
What do I need to do to get my systems of linear equations to align at each of the addition/subtraction/equals signs without manually adding silly things like \phantom{2} in front of variables with coefficient 1? Here's a general example where the + signs in the last equation are not vertically aligned with the + signs in the first two equations (not to mention the fiddling I did to get the vertical dots to be in a reasonable place):
\begin{align*}
a_{11}x_1 + a_{12}x_2 + \cdots + a_{1n}x_n & = b_1 \\
a_{21}x_1 + a_{22}x_2 + \cdots + a_{2n}x_n & = b_2 \\
\hspace{1in}\vdots \hspace{.8in} \\
a_{m1}x_1 + a_{m2}x_2 + \cdots + a_{mn}x_n & = b_m \\
\end{align*}
A more specific example:
\begin{align*}
x_1 + x_2 + 2x_3 &= 8 \\
-x_1 -2 x_2 + 3x_3 &= 1 \\
3x_1 -7 x_2 + 4x_3 &= 10 \\
\end{align*}
Should I just give up on align and use array?
alignatis good here: see these related questions – cmhughes Feb 09 '12 at 22:24