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JEE Main 202126 AugustEvening Shift
Exam
JEE Main
Year
2021
Date
26 August
Shift
Evening Shift
Subject
Mathematics
Chapter
Matrices

JEE Main 2021 · 26 August · Evening Shift · Mathematics · Matrices

Let A be a 3 × 3 real matrix. If det ( 2 Adj ( 2 Adj ( Adj ( 2A ) )...

Let AbeaA be a3 \times 3realmatrix.Ifreal matrix. Ifdet ( 2 Adj ( 2 Adj ( Adj ( 2A ) ) ) ) = {2}^{41},thenthevalueofthen the value ofdet (A2)\left({A}^{2}\right) equals ______.

Correct answer

0

Step-by-step solution

∴ | KA | = {K}^{n} | A | ,IfIfAisisn \times nmatrix</p><p>matrix</p><p>| Adj A | = | A{|}^{n - 1}IfIfAisisn \times nmatrix</p><p>matrix</p><p>| 2 Adj ( 2 Adj ( Adj ( 2A ) ) ) | = {2}^{41}</p><p></p><p>⇒ {2}^{3} | Adj ( 2 Adj ( Adj ( 2A ) ) ) | = {2}^{41}<br/><br />⇒ | Adj ( 2 Adj ( Adj ( 2A ) ) ) | = {2}^{38}<br/><br />⇒ ( | 2 Adj ( Adj ( 2A ) ) | {)}^{2} = {2}^{38}<br/><br />⇒ | 2 Adj ( Adj ( 2A ) ) | = {2}^{19}<br/><br />⇒ {2}^{3} | Adj ( Adj ( 2A ) ) | = {2}^{19}<br/><br />⇒ | Adj ( Adj ( 2A ) ) | = {2}^{16}<br/><br />⇒ ( | Adj ( 2A ) | {)}^{2} = {2}^{16}<br/><br />⇒ | Adj ( 2A ) | = {2}^{8}<br/><br />⇒ | ( 2A ) {|}^{2} = {2}^{8}<br/><br />⇒ | ( 2A ) | = {2}^{4}<br/><br />⇒ {2}^{3} | A | = {2}^{4}<br/><br />⇒ | A | = 2</p><p>So,∣A2∣=∣A∣2=4</p><p>So, \left|{A}^{2}\right| = {\left|A\right|}^{2} = 4

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