If \( A=[a_{ij}]_{3\times 3} \) is a square matrix, where \( a_{ij}=i-j+3 \), then the value of \( a_{21}+a_{31}-a_{23} \) is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 7
Putting the row number i and column number j into \( a_{ij}=i-j+3 \):
\( a_{21}=2-1+3=4 \)
\( a_{31}=3-1+3=5 \)
\( a_{23}=2-3+3=2 \)
\( a_{21}+a_{31}-a_{23}=4+5-2=7 \)