I have to admit, when having the problem already solved and checking my solution against the recital I was quite annoyed with the redundant verbosity of Ben. The following bragging about the source matrices didn't seem very useful as well… The last picture however was completely a revelation! I found it drawn impressively easy to understand and to the moment there has been no such a clear visualization in Mister Strang's lectures. I'm sure it is surely to follow. And thank you, Ben, for this such an interesting foresight!

Nice interpretation, especially from the last figure. Thanks Ben. Just a small error though, the N(B) has (-3/5 , -1, 1). You wrote the first coordinate as -3/2 on the figure.

## 9 Comments

## Adam D

Ben is just adorable. And cute, too 🙂

## Romina Liendro

Why (0 0 1) is not a pivot column?!

## Andrey Surovtsev

I have to admit, when having the problem already solved and checking my solution against the recital I was quite annoyed with the redundant verbosity of Ben. The following bragging about the source matrices didn't seem very useful as well…

The last picture however was completely a revelation! I found it drawn impressively easy to understand and to the moment there has been no such a clear visualization in Mister Strang's lectures. I'm sure it is surely to follow. And thank you, Ben, for this such an interesting foresight!

## Sam Mathew

Nice interpretation, especially from the last figure. Thanks Ben.

Just a small error though, the N(B) has (-3/5 , -1, 1). You wrote the first coordinate as -3/2 on the figure.

## And Wix

how old is this guy?

## Anna Sanderson

would be helpful if you wrote out how to solve things

## Wendy Wang

How come if the U has 2 pivots, then the column space dimension is 2?

## Zhi Shu

This is such a great problem for understanding the four matrices. Not really easy to explain.

## Nisarg Jain

How is it essentially the same thing to take pivot columns from L matrix as basis??