If A= [a_ i j ]= [ cc 2 & -1 -3 & 4 1 & 2 ] and B= [b_ i j ]= [ c… - Vidyadip

MCQ

If $A=\left[a_{i j}\right]=\left[\begin{array}{cc}2 & -1 \\ -3 & 4 \\ 1 & 2\end{array}\right]$ and $B=\left[b_{i j}\right]=\left[\begin{array}{ccc}2 & 3 & -5 \\ 1 & 4 & 9 \\ 0 & 7 & -2\end{array}\right]$, then value of $a_{11} b_{11}+a_{22} b_{22}$ is

A
8
✓
20
C
16
D
24

✓

Answer

Correct option: B.

20

(b) : We have, $A=\left[\begin{array}{cc}2 & -1 \\ -3 & 4 \\ 1 & 2\end{array}\right]$ and $B=\left[\begin{array}{ccc}2 & 3 & -5 \\ 1 & 4 & 9 \\ 0 & 7 & -2\end{array}\right]$
Here, $a_{11}=2, a_{22}=4, b_{11}=2, b_{22}=4$
$
\therefore \quad a_{11} b_{11}+a_{22} b_{22}=2(2)+4(4)=4+16=20
$

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