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If A is a square matrix of order 3 such ...

If `A` is a square matrix of order `3` such that `|A|=5`, then `|Adj(4A)|=`

A

`5^(3)xx4^(2)`

B

`5^(2)xx4^(3)`

C

`5^(2)xx16^(3)`

D

`5^(3)xx16^(2)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the determinant of the adjoint of the matrix \(4A\) given that the determinant of matrix \(A\) is \(5\) and \(A\) is a square matrix of order \(3\). ### Step-by-step Solution: 1. **Understanding the adjoint of a scalar multiple of a matrix**: The formula for the adjoint of a scalar multiple of a matrix is given by: \[ \text{Adj}(kA) = k^{n-1} \cdot \text{Adj}(A) \] where \(n\) is the order of the matrix. In this case, \(k = 4\) and \(n = 3\). 2. **Applying the formula**: Using the formula, we can express the adjoint of \(4A\): \[ \text{Adj}(4A) = 4^{3-1} \cdot \text{Adj}(A) = 4^2 \cdot \text{Adj}(A) = 16 \cdot \text{Adj}(A) \] 3. **Finding the determinant of the adjoint**: The determinant of the adjoint of a matrix \(A\) is given by: \[ |\text{Adj}(A)| = |A|^{n-1} \] For our matrix \(A\), since \(|A| = 5\) and \(n = 3\): \[ |\text{Adj}(A)| = |A|^{3-1} = |A|^2 = 5^2 = 25 \] 4. **Calculating the determinant of \(4A\)**: The determinant of a scalar multiple of a matrix is given by: \[ |kA| = k^n \cdot |A| \] Therefore, for \(4A\): \[ |4A| = 4^3 \cdot |A| = 64 \cdot 5 = 320 \] 5. **Finding the determinant of the adjoint of \(4A\)**: Now, we can find the determinant of the adjoint of \(4A\) using the previously mentioned property: \[ |\text{Adj}(4A)| = |4A|^{n-1} = |4A|^{3-1} = |4A|^2 \] Substituting the value of \(|4A|\): \[ |\text{Adj}(4A)| = 320^2 \] 6. **Calculating \(320^2\)**: \[ 320^2 = 102400 \] ### Final Answer: Thus, the value of \(|\text{Adj}(4A)|\) is \(102400\).

To solve the problem, we need to find the determinant of the adjoint of the matrix \(4A\) given that the determinant of matrix \(A\) is \(5\) and \(A\) is a square matrix of order \(3\). ### Step-by-step Solution: 1. **Understanding the adjoint of a scalar multiple of a matrix**: The formula for the adjoint of a scalar multiple of a matrix is given by: \[ \text{Adj}(kA) = k^{n-1} \cdot \text{Adj}(A) ...
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Knowledge Check

  • If A is a square matrix of order 3 such that |A^(T)| = 5 , then value of |2A|= a) 25 b) 10 c) 20 d) 40

    A
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    B
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