Question:

Calculate the determinant of the matrix:
 


 

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When faced with complex matrices, break down the matrix into simpler parts or look for patterns in the matrix to aid in the calculation.
Updated On: Mar 12, 2025
  • \((a - b)(b - c)(c - a)\)
  • \((a + b)(b + c)(c + a)\)
  • \(2abc\)
  • \(4abc\)
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The Correct Option is D

Solution and Explanation

Step 1: Setting up the matrix for determinant calculation. We are given the matrix: \[ M = \begin{bmatrix} \frac{a^2 + b^2}{c} & c & c
a & \frac{b^2 + c^2}{a} & a
b & b & \frac{c^2 + a^2}{b} \end{bmatrix} \] Step 2: Calculate the determinant. To find the determinant of the 3x3 matrix \( M \), we use the formula for the determinant of a 3x3 matrix: \[ \text{det}(M) = m_{11}(m_{22}m_{33} - m_{23}m_{32}) - m_{12}(m_{21}m_{33} - m_{23}m_{31}) + m_{13}(m_{21}m_{32} - m_{22}m_{31}) \] where \( m_{ij} \) represents the element in the \( i \)-th row and \( j \)-th column of matrix \( M \). Substituting the elements of matrix \( M \): \[ \text{det}(M) = \left(\frac{a^2 + b^2}{c}\right)\left(\frac{b^2 + c^2}{a}\frac{c^2 + a^2}{b} - a \cdot b\right) - c\left(a \cdot \frac{c^2 + a^2}{b} - a \cdot b\right) + c\left(a \cdot b - b \cdot \frac{b^2 + c^2}{a}\right) \] Step 3: Simplification and result. Let's simplify each term step by step. 1. First term: \[ \left(\frac{a^2 + b^2}{c}\right)\left(\frac{b^2 + c^2}{a}\frac{c^2 + a^2}{b} - a \cdot b\right) \] Simplify the product inside the parentheses: \[ \frac{b^2 + c^2}{a} \cdot \frac{c^2 + a^2}{b} = \frac{(b^2 + c^2)(c^2 + a^2)}{ab} \] Thus, the first term becomes: \[ \frac{a^2 + b^2}{c} \left(\frac{(b^2 + c^2)(c^2 + a^2)}{ab} - ab\right) \] 2. Second term: \[ - c\left(a \cdot \frac{c^2 + a^2}{b} - a \cdot b\right) \] Simplify inside the parentheses: \[ a \cdot \frac{c^2 + a^2}{b} - a \cdot b = \frac{a(c^2 + a^2)}{b} - ab = \frac{a(c^2 + a^2) - a b^2}{b} = \frac{a(c^2 + a^2 - b^2)}{b} \] Thus, the second term becomes: \[ - c \cdot \frac{a(c^2 + a^2 - b^2)}{b} = -\frac{a c (c^2 + a^2 - b^2)}{b} \] 3. Third term: \[ c\left(a \cdot b - b \cdot \frac{b^2 + c^2}{a}\right) \] Simplify inside the parentheses: \[ a \cdot b - b \cdot \frac{b^2 + c^2}{a} = ab - \frac{b(b^2 + c^2)}{a} = \frac{a^2 b - b(b^2 + c^2)}{a} = \frac{b(a^2 - b^2 - c^2)}{a} \] Thus, the third term becomes: \[ c \cdot \frac{b(a^2 - b^2 - c^2)}{a} = \frac{b c (a^2 - b^2 - c^2)}{a} \] Combining all terms: \[ \text{det}(M) = \frac{a^2 + b^2}{c} \left(\frac{(b^2 + c^2)(c^2 + a^2)}{ab} - ab\right) - \frac{a c (c^2 + a^2 - b^2)}{b} + \frac{b c (a^2 - b^2 - c^2)}{a} \] After further algebraic simplification and recognizing symmetries, the determinant simplifies to: \[ \text{det}(M) = 4abc \] Final Answer: \[ \boxed{4abc} \]
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