How do you factor with the box method

With the box you have four squares the first square holds the first term and the last square holds the last term. ex problem 2x^2-x-1
       _x__  _-1_
 2x |  2x^2  -2 x  |                              multiply those numbers together
  1|  1x_-1_|                                    -2 so you want to look at the common factors that equal to -x -2 and 1 do it the take out the commons between those 1+2x and x-1

A box plot shows the interquartile range using a box. not sure how to factor