MCQ
Let ${\Delta _1} = \left| {\,\begin{array}{*{20}{c}}{{a_1}}&{{b_1}}&{{c_1}}\\{{a_2}}&{{b_2}}&{{c_2}}\\{{a_3}}&{{b_3}}&{{c_3}}\end{array}\,} \right|$ and ${\Delta _2} = \left| {\,\begin{array}{*{20}{c}}{{\alpha _1}}&{{\beta _1}}&{{\gamma _1}}\\{{\alpha _2}}&{{\beta _2}}&{{\gamma _2}}\\{{\alpha _3}}&{{\beta _3}}&{{\gamma _3}}\end{array}\,} \right|$, then ${\Delta _1} \times {\Delta _2}$ can be expressed as the sum of how many determinants
  • A
    $9$
  • B
    $3$
  • $27$
  • D
    $2$

Answer

Correct option: C.
$27$
c
(c) Each term in ${\Delta _1} \times {\Delta _2}$ is the sum of three terms. So each entry in ${C_1}$ or ${C_2}$ or ${C_3}$ in ${\Delta _1} \times {\Delta _2}$ is the sum of three terms. Hence, ${\Delta _1} \times {\Delta _2}$ can be written as the sum of $3 × 3 × 3 = 27$ determinants.

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