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Given that A = [π‘Žπ‘–π‘—] is a square matrix of order 3 Γ— 3 and |A| = βˆ’7, then the value of βˆ‘_(i=1) 3 a i2 A i2 " Β , where 𝐴 𝑖𝑗 denotes the cofactor of element π‘Žπ‘–π‘— Β is:

(a) 7Β  (b) βˆ’7Β  (c) 0Β  (d) 49

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Question 17 Given that A = [π‘Žπ‘–π‘—] is a square matrix of order 3 Γ— 3 and |A| = βˆ’7, then the value of βˆ‘_(𝑖=1)^3β–’"π‘Žπ‘–2𝐴𝑖2 " , where 𝐴𝑖𝑗 denotes the cofactor of element π‘Žπ‘–π‘— is: (a) 7 (b) βˆ’7 (c) 0 (d) 49 Now, = 𝒂_𝟏𝟐 𝑨_𝟏𝟐+𝒂_𝟐𝟐 𝑨_𝟐𝟐+𝒂_𝟐𝟐 𝑨_𝟏𝟐 = Sum of product of elements of Row R2 with its corresponding cofactors = Determinant of A = |A| = 7 So, the correct answer is (B)

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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.