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Question 1571: determinant of the matrix
1 2 -1 -2
1 2 1 2
1 0 0 1
0 1 1 0
Answer by khwang(438)   (Show Source):
You can put this solution on YOUR website! Adding the 2nd row to the first row, we have
2 4 0 0
1 2 1 2
1 0 0 1
0 1 1 0
Adding the 1st row times -1/2 row to the 2nd row, we have
2 4 0 0
0 0 1 2
1 0 0 1
0 1 1 0
to find the determinant by expanding along the 1st column, we have
|0 1 2| |4 0 0|
2|0 0 1| + |0 1 2|
|1 1 0| |1 1 0|
= 2 + 4(-2) = -6.
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