I believe that Mr. Strang is really amazing and incredible, but I got stuck when he said of "the pivot and free variables" , I mean he told us about the algorithm very well, but I am not able to connect these with that what does it mean to?? Why does non pivot columns can be considered anything?? And what are its effect on my graph if I wish to plot it on?? And what's the concept behind these pivot and free variables, how did it occur from anywhere??So , if you guys could help me out with this , it would really be appreciated!!####[]