Q- If A is a square matrix of order 2 and |A| = -5 , then find the value of |3.A| And |3.A^T|

We know that |k A| = kⁿ |A| where n is the order of the matrix . Also we know that from the properties of determinants that if you interchange the rows and columns of a determinant ,the value of the determinant remains the same . This in other words mean |A| = |A^T|.
So now given that n = 2 , |A| = -5
So |3A| = |3A^T​| = 3² |A| = 9 x -5 = -45.
Hope that helps.