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
𝑎11 𝐴21 + 𝑎12 𝐴22 + 𝑎13 𝐴23 = 0
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.
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