Answer
a) TRUE
b) FALSE
Work Step by Step
a) The cofactor expansion of det A down a column is equal to the cofactor expansion along a row. We will get the same number for det A so it TRUE
b) The determinant of a triangular matrix is the sum of the entries on the main diagonal is FALSE. Theorem 2 states: If A is a triangular matrix, then det A is the PRODUCT of the entries on the main diagonal of A.
