amsmath

aligning math equations in Latex

I am trying to align the following equations around the equal sign. What can I do? Thanks! I am using the AMSMath package $$m\ddot{x}_{1}-K(x_{2}+x_{12})+C(\dot{x}_{12}+\dot{x}_{2})+2C\dot{x}_{1} = fx_{1}$$ $$m\ddot{x}_{2}-K(x_{3}+x_{1})+C(\dot{x}_{1}+\dot{x}_{3})+2C\dot{x}_{2} = fx_{2}$$ $$m\ddot{x}_{3}-K(x_{4}+x_{2})+C(\dot{x}_{2}+\...

Typesetting a large matrix in LaTeX

I have a 3x12 matrix I'd like to input into my LaTeX (with amsmath) document but LaTeX seems to choke when the matrix gets larger then 3x10: \begin{equation} \textbf{e} = \begin{bmatrix} 1&1&1&1&0&0&0&0&-1&-1&-1&-1\\ 1&-1&0&0&1&1&-1&-1&0&0&1&-1\\ 0&0&1&-1&1&-1&1&-1&1&-1&0&0 \end{bmatrix} \end{equation} The error: Extra alignment tab...

How to fix this align environment a bit neater?

I'm writing a description of how recursive functions are applied within lists using the align environment from amsmath in LaTeX. Here's the code: \begin{align*} & \reduce (+, 0, & [1, 2, 3, 4]) \\ = & \reduce (+, 0 + 1, & [2, 3, 4]) \\ = & \reduce (+, 0 + 1 + 2, & [3, 4]) \\ = & \reduce (+, 0 +...