In Exercises 39 and 40, A is an $n \times n$ matrix. Mark each statement True or False. Justify each answer.
a. The cofactor expansion of det A down a column is equal to the cofactor expansion along a row.
b. The determinant of a triangular matrix is the sum of the entries on the main diagonal.
True, the expansion along any row or column will give you the same determinant
False, the determinant of a triangular matrix is the product of the entries on the main diagonal.
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