JEE AdvancedMathematicsMatrices and DeterminantsMCQ+3 / −1
Let be a 3 3 matrix and let , where for . If the determinant of P is 2, then the determinant of the matrix Q is
- A210
- B211
- C212
- D213
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Correct answer: D
-
We are given Also,
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Write the entries of in a factorized form:
This means can be written as where
\qquad D_2=\begin{bmatrix}2^1&0&0\\0&2^2&0\\0&0&2^3\end{bmatrix}.$$ -
Now use the determinant property:
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Compute the determinants of the diagonal matrices: and similarly,
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Therefore,
-
So the determinant of is
-
Comparing with the options:
- A:
- B:
- C:
- D:
Hence the correct option is D.
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