Question

Find K if the following matrices are singular.

`[(7, 3),(-2, "K")]`

Answer 1

Let A = `[(7, 3),(-2, "K")]`

Since A is a singular matrix,
|A| = 0

∴ `|(7, 3),(-2, "K")|` = 0

∴ 7K + 6 = 0
∴ 7K = – 6
∴ K = `(-6)/(7)`.