# Example 21 - Chapter 4 Class 12 Determinants (Term 1)

Last updated at Dec. 8, 2016 by Teachoo

Last updated at Dec. 8, 2016 by Teachoo

Transcript

Example 21 Find minors and cofactors of the elements a11, a21 in the determinant ∆ = a11a12a13a21a22a23a31a32a33 Minor of a11 = M11 = a11a12a13a21a22a23a31a32a33 = a22a23a32a33 = a22 a33 – a23 a32 Minor of a21 = M21 = a11a12a13a21a22a23a31a32a33 = a12a13a32a33 = a12 a33 – a32 a13 Cofactor of a11 = A11 = ( – 1)1+1 . M11 = ( –1)2 . (a22 a33 – a32 a23) = a22 a33 – a32 a23 Cofactor of a21 = A21 = ( – 1)2+1 . M21= ( – 1)3 . (a12 a33 – a32 a13) = ( – 1) . (a12 a33 – a32 a13) = a32 a13 – a12 a33

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Chapter 4 Class 12 Determinants (Term 1)

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About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.