Gujarati
3 and 4 .Determinants and Matrices
medium

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

$3$

C

$27$

D

$2$

Solution

(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.

Standard 12
Mathematics

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