The expansion of a 3 ( 3 determinant can be remembered by the following device. Write a second copy of the first two columns to the right of the matrix, and compute the determinant by multiplying entries on six diagonals:

Add the downward diagonal products and subtract the upward products. Use this method to compute the determinants in Exercises 1-2. Warning: This trick does not generalize in any reasonable way to 4 ( 4 or larger matrices.
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Transcribed Image Text:

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