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If matrix A=[x23ay−5bc0]A = \begin{bmatrix} x & 2 & 3 \\ a & y & -5 \\ b & c & 0 \end{bmatrix} is a skew-symmetric matrix, then

(A) x+y+c=5x + y + c = 5

(B) c=5c = 5

(C) a+b+c=0a + b + c = 0

(D) a+b−c=10a + b - c = 10

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

A skew-symmetric matrix satisfies the property AT=−AA^T = -A, which means A[i][j]=−A[j][i]A[i][j] = -A[j][i] for all elements.

For any skew-symmetric matrix, all diagonal elements must equal zero.

Position (1,1): x=0x = 0

Position (2,2): y=0y = 0

Position (3,3): already 00


For position (1,2) and (2,1):

A[1][2]=2A[1][2] = 2 and A[2][1]=aA[2][1] = a

2=−a2 = -a

a=−2a = -2


For position (1,3) and (3,1):

A[1][3]=3A[1][3] = 3 and A[3][1]=bA[3][1] = b

3=−b3 = -b

b=−3b = -3


For position (2,3) and (3,2):

A[2][3]=−5A[2][3] = -5 and A[3][2]=cA[3][2] = c

−5=−c-5 = -c

c=5c = 5


The values are: x=0x = 0, y=0y = 0, a=−2a = -2, b=−3b = -3, c=5c = 5

Checking statement (A): x+y+c=0+0+5=5x + y + c = 0 + 0 + 5 = 5 ✓

Checking statement (B): c=5c = 5 ✓

Checking statement (C): a+b+c=(−2)+(−3)+5=0a + b + c = (-2) + (-3) + 5 = 0 ✓

Checking statement (D): a+b−c=(−2)+(−3)−5=−10≠10a + b - c = (-2) + (-3) - 5 = -10 \neq 10 ✗


Statements (A), (B), and (C) are correct.

The correct answer is the option containing (A), (B) and (C) only.

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