1.5.2 Greatest hits from previous weeks

Greatest hits from previous weeks:

1.5.2.1 How can I get bold math symbols?

http://tex.stackexchange.com/questions/595/how-can-i-get-bold-math-symbols

To make Latin-letter variables bold I can use e.g. \mathbf{a}, but while putting Greek letters or symbols such as \nabla inside \mathbf doesn't cause any errors or warnings, it also doesn't do  ...
 

- asked by Michael Underwood (137 votes), answered by Mark Meckes (119 votes)

1.5.2.2 How can I split an equation over two lines

http://tex.stackexchange.com/questions/3782/how-can-i-split-an-equation-over-two-lines

I am having the following equation: 
\begin{equation} 
Q(\lambda,\hat{\lambda}) = -\frac{1}{2} P(O \mid \lambda ) \sum_s \sum_m \sum_t \gamma_m^{(s)} (t) \left( n \log(2 \pi ) + \log \left| C_m^{(s)}  ...
 

- asked by Peter Smit (83 votes), answered by Will Robertson (72 votes)