# Linear algebra - coordinates.

Can anyone explain exactly how you are supposed to apply coodinates in matrices? I am somewhat lost in class.

For example say, i have the coordinates A =
1 2
0 2 --> this is a 2 X 2 matrix

and I have to apply this to the basis

B =
1 0
0 0,

0 1
0 0,

0 1
0 1

-> The book gives the following matrix as the answer:

1 0 0
0 1 1
0 0 1

- But I still don't get how they got here. Can anyone outline the process?

Thank you!

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HallsofIvy
Homework Helper
No, I have no idea what you are talking about. (And I thought I knew a little about Linear Algebra!) I have never heard of "applying coordinates" to matrices, nor do I see how you are going from 2 by 2 matrices to a 3 by 3 matrix. Could you state the problem exactly as it is given?

I am sorry, this is supposed to be a change of basis problem. We are changing B to basis A.

Can you help?

we are trying to find the change of basis matrix.

HallsofIvy
Homework Helper
From what basis to what basis? And what space? The matrices you list as a basis are NOT a basis for M4, because there are only 3 of them.

No other info is given.