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|{:(a,b,c),(b,c,a),(c,a,b):}| is equal t...

`|{:(a,b,c),(b,c,a),(c,a,b):}|` is equal to

A

`a+b+c+abc`

B

`a^2+b^2+c^2+ab+bc+ca`

C

`3abc-a^2-b^3-c^3`

D

`a^3+b^3+c^3-3abc`

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The correct Answer is:
To find the value of the determinant \( D = \begin{vmatrix} a & b & c \\ b & c & a \\ c & a & b \end{vmatrix} \), we can expand it using the method of cofactor expansion along the first row. ### Step-by-Step Solution: 1. **Write the Determinant**: \[ D = \begin{vmatrix} a & b & c \\ b & c & a \\ c & a & b \end{vmatrix} \] 2. **Expand Along the First Row**: \[ D = a \begin{vmatrix} c & a \\ a & b \end{vmatrix} - b \begin{vmatrix} b & a \\ c & b \end{vmatrix} + c \begin{vmatrix} b & c \\ c & a \end{vmatrix} \] 3. **Calculate the 2x2 Determinants**: - For the first determinant: \[ \begin{vmatrix} c & a \\ a & b \end{vmatrix} = cb - a^2 \] - For the second determinant: \[ \begin{vmatrix} b & a \\ c & b \end{vmatrix} = bb - ac = b^2 - ac \] - For the third determinant: \[ \begin{vmatrix} b & c \\ c & a \end{vmatrix} = ba - c^2 \] 4. **Substituting Back**: \[ D = a(cb - a^2) - b(b^2 - ac) + c(ba - c^2) \] 5. **Distributing**: \[ D = acb - a^3 - b^3 + abc + abc - c^3 \] 6. **Combine Like Terms**: \[ D = 3abc - (a^3 + b^3 + c^3) \] ### Final Answer: \[ D = 3abc - (a^3 + b^3 + c^3) \]
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AAKASH INSTITUTE ENGLISH-DETERMINANTS -SECTION A
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