Determinant Practice Questions Ques2
Question: What is the cofactor of the element $a_{12}$ in a $3 \times 3$ matrix $A$?
Options:
(A) $(-1)^{1+1}$ times the minor of $a_{12}$
(B) $(-1)^{2+1}$ times the minor of $a_{12}$
(C) $(-1)^{1+2}$ times the minor of $a_{12}$
(D) $(-1)^{2+2}$ times the minor of $a_{12}$
Show Answer
Answer: C
Explanation:
(A) Incorrect. This would be the cofactor of $a_{11}$.
(B) Incorrect. This would be the cofactor of $a_{21}$.
(C) Correct. The cofactor of $a_{12}$ is $(-1)^{1+2}$ times the minor of $a_{12}$.
(d) Incorrect. This would be the cofactor of $a_{22}$.
BETA
