How do you factor with the box method

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

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