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Which of the Following is Not Correct? (A) | a | = | a T | , Where a = [ a I J ] 3 × 3 (B) | K a | = | K 3 | , Where a = [ a I J ] 3 × 3 (C) If a is a Skew-symmetric Matrix of Odd Order, Then - Mathematics

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Question

Which of the following is not correct?

Options

  • \[|A| = | A^T |,\text{ where }A = \left[ a_{ij} \right]_{3 \times 3}\] 

  • \[|kA| = | k^3 |,\text{ where }A = \left[ a_{ij} \right]_{3 \times 3}\]

  • If A is a skew-symmetric matrix of odd order, then |A| = 0

  • \[\begin{vmatrix}a + b & c + d \\ e + f & g + h\end{vmatrix} = \begin{vmatrix}a & c \\ e & g\end{vmatrix} + \begin{vmatrix}b & d \\ f & h\end{vmatrix}\]

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Solution

(d) \[\begin{vmatrix}a + b & c + d \\ e + f & g + h\end{vmatrix} = \begin{vmatrix}a & c \\ e & g\end{vmatrix} + \begin{vmatrix}b & d \\ f & h\end{vmatrix}\]

\[\begin{vmatrix} a + b & c + d\\e + f & g + h \end{vmatrix} = \begin{vmatrix} a + b & c\\e + f & g \end{vmatrix} + \begin{vmatrix} a + b & d\\e + f & h \end{vmatrix}\]
\[ = \begin{vmatrix} a & c\\e & g \end{vmatrix} + \begin{vmatrix} b & c\\f & g \end{vmatrix} + \begin{vmatrix} a & d \\e & h \end{vmatrix} + \begin{vmatrix} b & d\\f & h \end{vmatrix}\]

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Chapter 6: Determinants - Exercise 6.7 [Page 93]

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RD Sharma Mathematics [English] Class 12
Chapter 6 Determinants
Exercise 6.7 | Q 2 | Page 93

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