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Let A= [[a,b,c],[p,q,r],[x,y,z]] and sup...

Let `A= [[a,b,c],[p,q,r],[x,y,z]]` and suppose then det (A) = 2, then det (B) equals, where `B = [[4x,2a,-p],[4y, 2b, -q],[4z, 2c, -r]]`

A

-2

B

-8

C

-16

D

8

Text Solution

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The correct Answer is:
To find the determinant of the matrix \( B \) given that the determinant of matrix \( A \) is \( 2 \), we will follow these steps: Given: \[ A = \begin{bmatrix} a & b & c \\ p & q & r \\ x & y & z \end{bmatrix} \] and \[ \text{det}(A) = 2 \] We need to find: \[ B = \begin{bmatrix} 4x & 2a & -p \\ 4y & 2b & -q \\ 4z & 2c & -r \end{bmatrix} \] ### Step 1: Factor out constants from the determinant Using the property of determinants that allows us to factor out constants from rows or columns, we can rewrite the determinant of \( B \): \[ \text{det}(B) = \text{det}\left(\begin{bmatrix} 4x & 2a & -p \\ 4y & 2b & -q \\ 4z & 2c & -r \end{bmatrix}\right) \] We can factor out \( 4 \) from the first column, \( 2 \) from the second column, and \( -1 \) from the third column: \[ \text{det}(B) = 4 \cdot 2 \cdot (-1) \cdot \text{det}\left(\begin{bmatrix} x & a & p \\ y & b & q \\ z & c & r \end{bmatrix}\right) \] This simplifies to: \[ \text{det}(B) = -8 \cdot \text{det}\left(\begin{bmatrix} x & a & p \\ y & b & q \\ z & c & r \end{bmatrix}\right) \] ### Step 2: Relate the determinant of \( B \) to \( A \) Notice that the matrix inside the determinant is a rearrangement of the columns of \( A \). Specifically, we can express it as: \[ \text{det}\left(\begin{bmatrix} x & a & p \\ y & b & q \\ z & c & r \end{bmatrix}\right) = \text{det}(A) \] However, we will need to account for the column swaps. ### Step 3: Interchange columns 1. Interchange column 1 and column 2: \[ \text{det}\left(\begin{bmatrix} x & a & p \\ y & b & q \\ z & c & r \end{bmatrix}\right) = -\text{det}\left(\begin{bmatrix} a & x & p \\ b & y & q \\ c & z & r \end{bmatrix}\right) \] 2. Interchange column 2 and column 3: \[ \text{det}\left(\begin{bmatrix} a & x & p \\ b & y & q \\ c & z & r \end{bmatrix}\right) = -\text{det}(A) \] ### Step 4: Final expression for \( \text{det}(B) \) Combining these results, we have: \[ \text{det}(B) = -8 \cdot (-\text{det}(A)) = 8 \cdot \text{det}(A) \] Substituting \( \text{det}(A) = 2 \): \[ \text{det}(B) = 8 \cdot 2 = 16 \] ### Step 5: Apply the negative sign from the earlier factorization Thus, we have: \[ \text{det}(B) = -16 \] ### Conclusion The final result is: \[ \text{det}(B) = -16 \]

To find the determinant of the matrix \( B \) given that the determinant of matrix \( A \) is \( 2 \), we will follow these steps: Given: \[ A = \begin{bmatrix} a & b & c \\ p & q & r \\ x & y & z ...
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