Determinant Practice Questions Ques6
Question: For a $3 \times 3$ matrix $A$, if the cofactor of $a_{12}$ is $6$, what is the minor of $a_{12}$?
Options:
(A) $6$
(B) $-6$
(C) $3$
(D) $-3$
Show Answer
Answer: B
Explanation:
(A) Incorrect. The sign is wrong.
(B) Correct. The cofactor of $a_{12}$ is $(-1)^{1+2} \times \text{minor of } a_{12} = -\text{minor of } a_{12}$. Therefore, the minor of $a_{12}$ is $-6$.
(C) Incorrect. The value is wrong.
(D) Incorrect. Both the sign and value are wrong.
BETA
