Determinant Practice Questions Ques4
Question: For a $3 \times 3$ matrix $A$, if the cofactor of $a_{23}$ is $-7$, what is the minor of $a_{23}$?
Options:
(A) $7$
(B) $-7$
(C) $-14$
(D) $14$
Show Answer
Answer: A
Explanation:
(A) Correct. The cofactor of $a_{23}$ is $(-1)^{2+3} \times \text{minor of } a_{23} = -\text{minor of } a_{23}$. Therefore, the minor of $a_{23}$ is $7$.
(B) Incorrect. The sign is wrong.
(C) Incorrect. The value is wrong.
(D) Incorrect. Both the sign and value are wrong.
BETA
