Howard S. Hamilton ........................................................................................hsh2760
Week 11 ...........................................................................................................7-1-14
http://www.cs.tamu.edu/people/hamilton/math-311/week11/7-1-14.html


Calculate the determinate of the following matrix:    

image1.gif (1480 bytes)


Solution:

The determinate of this matrix may be calculated using the cofactor expansion algorithm where:
image5.gif (1235 bytes)

where Ajk is the matrix obtained by omitting the row and column
of A containing ajk.

Using this method, we expand the 4x4 matrix into a sum of 4 determinates of 3x3 matrices:

1*detimage6.gif (1269 bytes) -3*detimage8.gif (1275 bytes)+0* detimage9.gif (1271 bytes)+0* det image10.gif (1272 bytes)

Since the last matraces will be zero, we can exclude them from our calculations.

Calculating the first two determinates using the same method:

det image6.gif (1269 bytes) = 0 - 5* detimage12.gif (1068 bytes) + 7 *image13.gif (1064 bytes)

det image6.gif (1269 bytes) = 0 - 5*(-32)  + 7 *(-24)

det image6.gif (1269 bytes) = -8

Additionally

det image8.gif (1275 bytes) = 0 - 5* detimage12.gif (1068 bytes) + 7 *image13.gif (1064 bytes)

det image8.gif (1275 bytes) = 0 - 5*(-16) + 7*(-12)

det image8.gif (1275 bytes) = -4

Therefore:

1*(-8) -3*(-4) = 4

Which is the answer we seek.