Explanation
By the properties of determinants all the above I, II, and III are correct.
Determinant of skew symmetric matrix of odd order is zero. Here it is of order 3
∴Statement I is correct.
det(AT) = det(A)
det(–A) = (–1)n det A
∴Statement II is incorrect.
Trace of A = 2a, will be divisible by P if a = 0
|A| = a2 – bc, for (a2 – bc) to be divisible by P
∴ (P – 1) ordered pairs (b, c) for any value of a
∴Required number of ways = (P – 1)2
The number of A in TP such that det (A) is not divisible by P is
Tr(A) = P(P – 1); of these (P – 1)2 are such that P divides |A|.
Number of matrices for which P divides tr(A) and P does not divide |A| are (P – 1)2.
∴Total number = (P – 1) P2 – (P – 1)2 + (P – 1)2 = P3 – q3
The sum of the product of the elements of row with cofactors of the corresponding elements is slways equal to the value of the determinant. i.e., |A|. [determinant of A]
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