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If A=[aij]3×2A = [a_{ij}]_{3 \times 2} where aij=i+ja_{ij} = i + j, then

(A) A is a square matrix

(B) a21+a32=8a_{21} + a_{32} = 8

(C) Number of elements in A is 6

(D) Transpose of A=[233445]A = \begin{bmatrix}2 & 3 \\ 3 & 4 \\ 4 & 5\end{bmatrix}

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

Given A=[aij]3×2A = [a_{ij}]_{3 \times 2} where aij=i+ja_{ij} = i + j

The notation 3×23 \times 2 means A has 3 rows and 2 columns.

The formula aij=i+ja_{ij} = i + j gives each element by adding the row number and column number.


Computing all elements using aij=i+ja_{ij} = i + j:

a11=1+1=2a_{11} = 1 + 1 = 2

a12=1+2=3a_{12} = 1 + 2 = 3

a21=2+1=3a_{21} = 2 + 1 = 3

a22=2+2=4a_{22} = 2 + 2 = 4

a31=3+1=4a_{31} = 3 + 1 = 4

a32=3+2=5a_{32} = 3 + 2 = 5

Therefore: A=[233445]A = \begin{bmatrix}2 & 3 \\ 3 & 4 \\ 4 & 5\end{bmatrix}


Checking option (A): A is a square matrix

A square matrix has equal rows and columns.

Matrix A is 3×23 \times 2 with 3 rows and 2 columns.

Since 3≠23 \neq 2, option (A) is false.


Checking option (B): a21+a32=8a_{21} + a_{32} = 8

a21=2+1=3a_{21} = 2 + 1 = 3

a32=3+2=5a_{32} = 3 + 2 = 5

a21+a32=3+5=8a_{21} + a_{32} = 3 + 5 = 8

Option (B) is true.


Checking option (C): Number of elements in A is 6

Total elements =rows×columns= \text{rows} \times \text{columns}

Total elements =3×2= 3 \times 2

Total elements =6= 6

Option (C) is true.


Checking option (D): Transpose of A=[233445]A = \begin{bmatrix}2 & 3 \\ 3 & 4 \\ 4 & 5\end{bmatrix}

The matrix shown is A itself, not its transpose.

The transpose swaps rows and columns.

AT=[234345]A^T = \begin{bmatrix}2 & 3 & 4 \\ 3 & 4 & 5\end{bmatrix}

This is a 2×32 \times 3 matrix.

Option (D) is false.


Only statements (B) and (C) are correct.

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