deletions | additions       diff --git a/4-Dimensions.tex b/4-Dimensions.tex  index 4752dae..b942e6e 100644  --- a/4-Dimensions.tex  +++ b/4-Dimensions.tex 
...
x_3 & y_3 & z_3 \\  \end{vmatrix}  +...  \end{equation}  Therefore \begin{equation}  Q(r_1,r_2,r_3,r_4)=r_1\cdot(r_2\times r_3)+...  \end{equation}