What number is 80% of 65
2 answers:
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(i) Use the formula for the determinant of a 2×2 matrix.
(ii) The adjugate matrix is the transpose of the cofactor matrix of A. (These days, the "adjoint" of a matrix X is more commonly used to refer to the conjugate transpose of X, which is not the same.)
The cofactor of the (i, j)-th entry of A is the determinant of the matrix you get after deleting the i-th row and j-th column of A, multiplied by . If C is the cofactor matrix of A, then
Then the adjugate of A is the transpose of C,
(iii) The inverse of A is equal to 1/det(A) times the adjugate:
(iv) The system of equations translates to the matrix equation
Multiplying both sides on the left by the inverse of A gives
