1.

Find the determinant of the matrix \(\begin{vmatrix} \rm x-y & \rm y-z & \rm z-x\\ \rm y-z & \rm z-x & \rm x-y \\ \rm z-x & \rm x-y & \rm y-z \end{vmatrix}\)1. x + y + z2. x2 + y2 + z23. 04. (x + y + z)2 - xyz

Answer» Correct Answer - Option 3 : 0

Concept:

Properties of Determinant of a Matrix:

  • If each entry in any row or column of a determinant is 0, then the value of the determinant is zero.
  • For any square matrix say A, |A| = |AT|.
  • If we interchange any two rows (columns) of a matrix, the determinant is multiplied by -1.
  • If any two rows (columns) of a matrix are same then the value of the determinant is zero.

 

Calculation:

\(\begin{vmatrix} \rm x-y & \rm y-z & \rm z-x\\ \rm y-z & \rm z-x & \rm x-y \\ \rm z-x & \rm x-y & \rm y-z \end{vmatrix}\)

Apply R1 → R1 + R2 + R3, We get

\(\begin{vmatrix} \rm 0 & \rm 0 & \rm 0\\ \rm y-z & \rm z-x & \rm x-y \\ \rm z-x & \rm x-y & \rm y-z \end{vmatrix}\)

As we can see that the entry of the first row is zero. 

We know that,

If each entry in any row or column of a determinant is 0, then the value of the determinant is zero.

∴ \(\begin{vmatrix} \rm x-y & \rm y-z & \rm z-x\\ \rm y-z & \rm z-x & \rm x-y \\ \rm z-x & \rm x-y & \rm y-z \end{vmatrix}\) = 0



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