3 and 4 .Determinants and Matrices
easy

જો $A=\left[\begin{array}{ll}6 & 9 \\ 2 & 3\end{array}\right]$ અને $B=\left[\begin{array}{lll}2 & 6 & 0 \\ 7 & 9 & 8\end{array}\right]$ તો $AB$ શોધો. 

A

$\left[\begin{array}{ccc}75 & 117 & 72 \\ 25 & 39 & 24\end{array}\right]$

B

$\left[\begin{array}{ccc}75 & 117 & 72 \\ 25 & 39 & 24\end{array}\right]$

C

$\left[\begin{array}{ccc}75 & 117 & 72 \\ 25 & 39 & 24\end{array}\right]$

D

$\left[\begin{array}{ccc}75 & 117 & 72 \\ 25 & 39 & 24\end{array}\right]$

Solution

The matrix $A$ has $2$ columns which is equal to the number of rows of $B$.

Hence $AB$ is defined. Now

$A B=\left[\begin{array}{lll}6(2)+9(7) & 6(6)+9(9) & 6(0)+9(8) \\ 2(2)+3(7) & 2(6)+3(9) & 2(0)+3(8)\end{array}\right]$

$=\left[\begin{array}{ccc}12+63 & 36+81 & 0+72 \\ 4+21 & 12+27 & 0+24\end{array}\right]=\left[\begin{array}{ccc}75 & 117 & 72 \\ 25 & 39 & 24\end{array}\right]$

Standard 12
Mathematics

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