## writing out a matrix

hey guys, so im new to linear algebra and is just learning matrix algebra

let A = a_ij be a 2 x 3 matrix, defined by a_ij = 2i + j. Write out A

would it just be
|1 2 3|
|4 5 6|
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 No. Remember that the i and j in your a_ij correspond to the ith row and the jth column.
 what does that mean? as in what does the 2i + j do to the function?

## writing out a matrix

It just like evaluating a regular function such as
f(x) = x^2 + 6x + 4 at x = 2.

So if you want to find the entry in the ith row and jth column then you evaluate
a$$_{i,j}$$ = 2i + j at the ith row and jth column.
 ok i dont know if im following you would it be something like this? |3 4 5| |5 6 7| and if it is i still dont get it :S
 Thats exactly right! If you don't get it then how did you get the right answer?
 i think i get, would it be like this |(2(1) + 1) (2(1) + 2) (2(1) + 3) | |(2(2) + 1) (2(2) + 2) (2(2) + 3| so basically you plug the i and j value depending which position in the matrix you are in?
 exactly!