Question

What do the commas mean here. Uploading a pic

Answer 1

The comma is use in
numbers and mathematics to
make to numbers easier to
read. ( avoid confusion )

Answer 2

ironic cuzz it is confusing me

I understand when it is a pair like x,y

but what does it mean in the context of linear algebra?

Answer 3

It's just to separate numbers and letters.

Answer 4

Generally in linear algebra you need a double index to denote the row and column youre in (in reference to some matrix). Thats what those commas look like they are doing to me. \[a_{i,j}\]means the element in the i-th row, j-th column.