fuckyeahmath: tristn: Rule of Sarrus: To calculate the determinant of a 3x3 matrix, add the products along the solid diagonals and subtract the products along the dashed diagonals. I have an exam in linear algebra today, and this rule is very handy. But it is mentioned nowhere in my textbook, which I now resent greatly. If you ask me, the only thing the text has on Wikipedia are the exercises and the paper to write on. Then again it’s also heavy and not free. I have never liked this method.  It has always seemed childish in my mind. I prefer the columns method (I dont know the proper name). | i      j      k | |a11 a12 a13| |a21 a22 a23| = i(a12*a23-a13*a22)-j(a11*a23-a13*a21)+k(a11*a22-a12*a21) this is done by striking the column and row of the vector you are working with

fuckyeahmath:

tristn:

Rule of Sarrus: To calculate the determinant of a 3x3 matrix, add the products along the solid diagonals and subtract the products along the dashed diagonals.

I have an exam in linear algebra today, and this rule is very handy. But it is mentioned nowhere in my textbook, which I now resent greatly. If you ask me, the only thing the text has on Wikipedia are the exercises and the paper to write on. Then again it’s also heavy and not free.

I have never liked this method.  It has always seemed childish in my mind.

I prefer the columns method (I dont know the proper name).

| i      j      k |

|a11 a12 a13|

|a21 a22 a23|

= i(a12*a23-a13*a22)-j(a11*a23-a13*a21)+k(a11*a22-a12*a21)

this is done by striking the column and row of the vector you are working with