begin{align}and\end{align}commands to correctly display the aligned mathematics. Here we use the ampersand (&) command to ensure the equations always line up as desired. We also see how to use the\nonumbercommand to remove the equation number from intermediate steps in the equation if ...
Use \vec{x} to make a vector quantity in LaTeX. I don't think this would work for copying into Word. If you want to make a vector in Word, and you don't want to use the built in Equation functionality, just use an arrow object and manually position it above the ...