Question

Solve the following :

Find k, if `[(7, 3),(5, "k")]` is a singular matrix.

Answer 1

Let A = `[(7, 3),(5, "k")]` 
Since A is singular matrix,
|A| = 0

∴ `|(7, 3),(5, "k")|` = 0

∴ 7k – 15 = 0
∴ 7k = 15
∴ k = `(15)/(7)`.