Is A is square matrix of order 3 and |2A| = k|A|, then find the value of k.

If A is an invertible square matrix of order 3 and |A| = 5, then find the value of |adj A|.
If A and B are square matrices of order 3 such that |A| = –1, |B| = 3, then find the value of |2AB|.
If the determinant of matrix A of order 3 × 3 is of value 4, write the value of |3A|.
If a line has direction ratios 2, – 1, – 2, then what are its direction cosines ?