Engineering Board Exam Reviewer · Matrix Inverse and Cofactors · medium

Find the cofactor C23 of A= bmatrix2&1&3\0&4&-1\5&2&6 bmatrix.

  1. -1
  2. 1
  3. 2
  4. -2

Answer

B. 1

Solution

Delete row 2 and column 3: M23= vmatrix2&1\5&2 vmatrix=4-5=-1. Then C23=(-1)2+3M23=(-1)(-1)=1.

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