Question 71Asked in BPSC TRE 3.0 (2024) Mathematics Class 11-12

If A = [[1, 2], [−1, 1]] (rows), then the value of A² − 2A + 2I is equal toयदि A = [[1, 2], [−1, 1]] (पंक्तियाँ) एक आव्यूह है, तब A² − 2A + 2I का मान है

यदि A = [[1, 2], [−1, 1]] (पंक्तियाँ) एक आव्यूह है, तब A² − 2A + 2I का मान है
  1. AII
  2. BOO
  3. C−I−I
  4. DMore than one of the aboveउपर्युक्त में से एक से अधिक
  5. ENone of the aboveउपर्युक्त में से कोई नहीं
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Correct answer: (C) −I−I

Explanation

A² = [[1−2, 2+2], [−1−1, −2+1]] = [[−1, 4], [−2, −1]]. Then A² − 2A = [[−1−2, 4−4], [−2+2, −1−2]] = [[−3, 0], [0, −3]], and adding 2I gives [[−1, 0], [0, −1]] = −I.A² = [[1−2, 2+2], [−1−1, −2+1]] = [[−1, 4], [−2, −1]]। तब A² − 2A = [[−1−2, 4−4], [−2+2, −1−2]] = [[−3, 0], [0, −3]], और 2I जोड़ने पर [[−1, 0], [0, −1]] = −I।

From BPSC TRE 3.0 (2024) Mathematics Class 11-12 — Previous Year Paper

This is question 71 of BPSC TRE 3.0 (2024) Mathematics Class 11-12 — Previous Year Paper. See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.