Check sibling questions

If A = [8(1 -1 0 2 3 4 0 1 2)] and B = [8(2 2 -4 -4 2 -4 2 -1 5)], then
(a) A−1 = B          (b) A−1 = 6B 
(c) B−1 = B          (d) B−1 = 1/6 A

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Transcript

Question 25 If A = [■8(1&−1&[email protected]&3&[email protected]&1&2)] and B = [■8(2&2&−[email protected]−4&2&−[email protected]&−1&5)], then (a) A−1 = B (b) A−1 = 6B (c) B−1 = B (d) B−1 = 1/6 A Let’s try multiplying AB AB = [■8(1&−1&[email protected]&3&[email protected]&1&2)] [■8(2&2&−[email protected]−4&2&−[email protected]&−1&5)] = [■8(2+4+0&2−2+0&−[email protected]−12+8&4+6−2&−8−[email protected]−4+4&0+2−2&0−4+10)] = [■8(6&0&[email protected]&6&[email protected]&0&6)] = 6[■8(1&0&[email protected]&1&[email protected]&0&1)] = 6I Thus, AB = 6I 𝟏/𝟔 AB = I So, we can say B−1 = 𝟏/𝟔 A So, the correct answer is (D)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.