Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Determinants

Question:

Let $\{D_1, D_2, D_3,...., D_n\}$ be the set of all third order determinants that can be made with the distinct non-zero real numbers $a_1, a_2,...., a_n$, then

Options:

$\sum\limits_{i=1}^{n}D_i=1$

$\sum\limits_{i=1}^{n}D_i=0$

$D_i =D_j$ for all i, j

none of these

Correct Answer:

$\sum\limits_{i=1}^{n}D_i=0$

Explanation:

Total number of third order determinants with distinct non-zero real numbers $a_1, a_2,...., a_n$ as elements is 9!. These determinants can be grouped into two groups each containing $\frac{9!}{2}$ determinants such that corresponding to each determinant in a group there is another determinant in the other group which is obtained by interchanging two consecutive rows of the determinant in first group.

Hence, $\sum\limits_{i=1}^{n}D_i=0$