If A=122212221, verify that A2−4A−5I=0.Answer: VerifiedSolutionCompute A2=A⋅A=988898889, and 4A=488848884, 5I=500050005.A2−4A−5I=9−4−58−88−88−89−4−58−88−88−89−4−5=000000000.Hence A2−4A−5I=0. Verified.CBSE Class 12 Board · 2008 · Subjective