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evaluate: |(a-b-c,2a,2a),(2b,b-c-a,2b),(...

evaluate: `|(a-b-c,2a,2a),(2b,b-c-a,2b),(2c,2c,c-a-b)|`

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To evaluate the determinant \[ D = \begin{vmatrix} a-b-c & 2a & 2a \\ 2b & b-c-a & 2b \\ 2c & 2c & c-a-b \end{vmatrix} \] we will follow a series of transformations to simplify the determinant. ### Step 1: Apply Row Transformation We will first transform the first row \( R_1 \) by adding the second row \( R_2 \) and the third row \( R_3 \) to it. This gives us: \[ R_1 \rightarrow R_1 + R_2 + R_3 \] Calculating this, we have: - First element: \( (a-b-c) + 2b + 2c = a + b + c \) - Second element: \( 2a + (b-c-a) + 2c = a + b + 3c \) - Third element: \( 2a + 2b + (c-a-b) = a + b + c \) So the new determinant becomes: \[ D = \begin{vmatrix} a+b+c & a+b+3c & a+b+c \\ 2b & b-c-a & 2b \\ 2c & 2c & c-a-b \end{vmatrix} \] ### Step 2: Factor Out Common Terms Now, we can factor out \( a+b+c \) from the first row: \[ D = (a+b+c) \begin{vmatrix} 1 & 1 & 1 \\ 2b & b-c-a & 2b \\ 2c & 2c & c-a-b \end{vmatrix} \] ### Step 3: Apply Column Transformation Next, we will perform column transformations to simplify the determinant further. We will transform \( C_1 \) by subtracting \( C_2 \) and \( C_3 \): \[ C_1 \rightarrow C_1 - C_2 \] \[ C_2 \rightarrow C_2 - C_3 \] This gives us: \[ D = (a+b+c) \begin{vmatrix} 1-1 & 1 & 1-1 \\ 2b - (b-c-a) & b-c-a - 2b & 2b \\ 2c - 2c & 2c - (c-a-b) & c-a-b \end{vmatrix} \] Calculating the new elements: - First row becomes \( (0, 1, 0) \) - Second row becomes \( (2b - (b-c-a), -b+c+a, 2b) = (b+c-a, -b+c+a, 2b) \) - Third row becomes \( (0, 2c - (c-a-b), c-a-b) = (0, a+b+c, c-a-b) \) So we have: \[ D = (a+b+c) \begin{vmatrix} 0 & 1 & 0 \\ b+c-a & -b+c+a & 2b \\ 0 & a+b+c & c-a-b \end{vmatrix} \] ### Step 4: Expand the Determinant Now we can expand the determinant using the first row: \[ D = (a+b+c) \cdot 0 - 1 \cdot \begin{vmatrix} b+c-a & 2b \\ 0 & c-a-b \end{vmatrix} \] Calculating this 2x2 determinant: \[ = (b+c-a)(c-a-b) \] Thus, we have: \[ D = (a+b+c) \cdot (b+c-a)(c-a-b) \] ### Final Result The final result is: \[ D = (a+b+c)^3 \]

To evaluate the determinant \[ D = \begin{vmatrix} a-b-c & 2a & 2a \\ 2b & b-c-a & 2b \\ 2c & 2c & c-a-b \end{vmatrix} ...
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