Question

Find k if matrix x 22 [ 7 -2 3 k ] is singular.​

Answer 1

Answer:

Given, A=[2−k123−k]

Also given A is singular.

⇒∣A∣=0

Thus ∣∣∣∣∣∣2−k123−k∣∣∣∣∣∣=0(2−k)(3−k)−2=0

⇒6−2k−3k+k2−2=0⇒k2−5k+4=0⇒k2−5k=−4⇒5k−k2=4