Matrices and Variables Help

[anicole]

Hi, I have a problem that is Matrix A*x = Matrix B. Solve for x. I've tried everything I know in excel and on my Ti-83 but I just can't get a correct answer. Here are the numbers:

Matrix A
1 2 -2 1
-3 -5 9 -4
-3 -4 13 -7
1 3 -1 5

Matrix B
0
-8
-16
-9

I know that the answer is going to be a 4x1. Thanks in advance.

 

[Deleted member 4993]

Hi, I have a problem that is Matrix A*x = Matrix B. Solve for x. I've tried everything I know in excel and on my Ti-83 but I just can't get a correct answer. Here are the numbers:

Matrix A
1              2                -2                 1
-3            -5                 9                -4
-3             -4               13                -7
1               3                -1                  5

Matrix B
0
-8
-16
-9

I know that the answer is going to be a 4x1. Thanks in advance.

Using excel (or calculator) - did you find the "inverse" of the matrix A?

 

[anicole]

Yes I know how to find the inverse. I think.

1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

 

[Deleted member 4993]

Yes I know how to find the inverse. I think.

1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

No - what you wrote is called an "identity matrix" - I

when you multiply a matrix by its inverse - you would get an identity matrix.

Study up on inverse matrix and how to find those through your calculator or excel.