Physics Forums (http://www.physicsforums.com/index.php)
-   Calculus & Beyond Homework (http://www.physicsforums.com/forumdisplay.php?f=156)
-   -   Linear algebra: Determinant (http://www.physicsforums.com/showthread.php?t=438004)

 _Bd_ Oct14-10 01:16 PM

Linear algebra: Determinant

1. The problem statement, all variables and given/known data

Evaluate the following determinant by expressing the matrix in upper triangular form.

2. Relevant equations

row operations.

3. The attempt at a solution

http://yfrog.com/jnscan0001ugj
http://img707.imageshack.us/img707/6379/scan0001ug.jpg
http://img707.imageshack.us/img707/6379/scan0001ug.jpg

I want to know what I did wrong there cause I cant figure it out
the calculator shows a different answer.

 Mark44 Oct14-10 01:29 PM

Re: Linear algebra: Determinant

In your 4th (or so) step, you replaced row 2 by 1/2 itself. Replacing a row by a nonzero multiple of itself is one row operation that changes the value of the determinant. The other row operation that does this is swapping two rows.

The correct value of the determinant is -17.

 All times are GMT -5. The time now is 08:33 AM.