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STATEMENT -1 All positive odd integral p...

STATEMENT -1 All positive odd integral powers of a skew - symmetric matrix are symmetric.
STATEMENT-2 : All positive even integral powers of a skew - symmetric matrix are symmetric.
STATEMENT-3 If A is a skew - symmetric matrix of even order then `|A|` is perfect square

A

F T T

B

T T T

C

T F T

D

T T F

Text Solution

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The correct Answer is:
To solve the problem, we will analyze each statement regarding skew-symmetric matrices step by step. ### Step 1: Understanding Skew-Symmetric Matrices A matrix \( A \) is called skew-symmetric if it satisfies the condition: \[ A = -A^T \] where \( A^T \) is the transpose of \( A \). ### Step 2: Evaluating Statement 1 **Statement 1:** All positive odd integral powers of a skew-symmetric matrix are symmetric. To evaluate this, consider the odd power of a skew-symmetric matrix: \[ A^1 = A \] Taking the transpose: \[ A^T = (-A) = -A \] Since \( A^T \neq A \), the first statement is **false**. ### Step 3: Evaluating Statement 2 **Statement 2:** All positive even integral powers of a skew-symmetric matrix are symmetric. For even powers, consider: \[ A^2 = A \cdot A \] Taking the transpose: \[ (A^2)^T = (A \cdot A)^T = A^T \cdot A^T = (-A) \cdot (-A) = A^2 \] Since \( (A^2)^T = A^2 \), it follows that \( A^2 \) is symmetric. Therefore, all positive even integral powers of a skew-symmetric matrix are symmetric, making this statement **true**. ### Step 4: Evaluating Statement 3 **Statement 3:** If \( A \) is a skew-symmetric matrix of even order, then \( |A| \) is a perfect square. Consider a skew-symmetric matrix of even order (e.g., 2x2): \[ A = \begin{pmatrix} 0 & a \\ -a & 0 \end{pmatrix} \] The determinant is calculated as: \[ |A| = (0)(0) - (-a)(a) = a^2 \] Since \( a^2 \) is a perfect square, this statement holds true for any skew-symmetric matrix of even order. Thus, this statement is **true**. ### Summary of Statements - **Statement 1:** False - **Statement 2:** True - **Statement 3:** True
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Show that positive odd integral powers of a skew-symmetric matrix are skew-symmetric and positive even integral powers of a skew-symmetric matrix are symmetric.

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Knowledge Check

  • The inverse of skew - symmetric matrix of odd order

    A
    is a symmetric matrix
    B
    is a diogonal matrix
    C
    is a skew - symmetric matrix
    D
    does not exist
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