CBSE Class 12 Sample Paper for 2021 Boards

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Maths Class 12
Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Question 6 - CBSE Class 12 Sample Paper for 2021 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Last updated at August 14, 2026 by

Let A = [𝑎𝑖𝑗] be a square matrix of order 3×3 and |A|= -7. Find the value of
𝑎 11 𝐴 21 + 𝑎 12 𝐴 22 + 𝑎 13 𝐴 23  where 𝐴 𝑖𝑗 is the cofactor of element 𝑎 𝑖j

Let A = [aij] be a square matrix of order 3×3 and |A|= -7. Find value

 

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Transcript

Question 6 Let A = [𝑎𝑖𝑗] be a square matrix of order 3 × 3 and |A|= −7. Find the value of 𝑎11 𝐴21 + 𝑎12 𝐴22 + 𝑎13 𝐴23 where 𝐴𝑖𝑗 is the cofactor of element 𝑎𝑖j We know that If elements of a row (or column) are multiplied with cofactors of any other row (or column), then their sum is zero Thus, 𝑎11 𝐴21 + 𝑎12 𝐴22 + 𝑎13 𝐴23 = 0

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