Latex errors:
http://tug.org/errors.html
Has the the solution for the annoying hyperref problem
Single numbering for multi-line equation with braces :
\begin{equation}\label{xyzeq}
\left. \begin{aligned} LHS &= RHS \\
LHS &= RHS \\
LHS &= RHS
\end{aligned}
\right \}
\end{equation}
Brackets around fractions :
You need to tell LaTeX that those parentheses are around the fraction. One way is with the left and right macros:
\left(\frac{df}{dt}\right)
Blank Spaces in math mode :
http://tug.org/errors.html
Has the the solution for the annoying hyperref problem
Single numbering for multi-line equation with braces :
\begin{equation}\label{xyzeq}
\left. \begin{aligned} LHS &= RHS \\
LHS &= RHS \\
LHS &= RHS
\end{aligned}
\right \}
\end{equation}
Brackets around fractions :
You need to tell LaTeX that those parentheses are around the fraction. One way is with the left and right macros:
\left(\frac{df}{dt}\right)
Blank Spaces in math mode :
\, (thinspace)
\; (thickspace)
\quad (quadspace)
\qquad (double quadspace)
\! (negative thinspace)
Figure~\ref{toucan} shows a photograph of a toucan.
The tilde (~) in the above example is a special symbol within Latex. It represents a non-breaking space. It is useful here because it keeps 'Figure' and what ever number it \ref refers to as a single unit, and won't get split over lines or pages. 
