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Matrix A=[(1,2,3),(1,1,5),(2,4,7)], then...

Matrix `A=[(1,2,3),(1,1,5),(2,4,7)]`, then the value of `a_(31)A_(31)+a_(32)A_(32)+a_(33)A_(33)` is

A

1

B

13

C

`-1`

D

`-13`

Text Solution

Verified by Experts

The correct Answer is:
C
We have,
`A=[(1,2,3),(1,1,5),(2,4,7)]`
`a_(31)=2, a_(32)=4, a_(33)=7`
and `A_(31)=|(2,3),(1,5)|=10-3=7`
`A_(32)=-|(1,3),(1,5)|=-(5-3)=-2`
`A_(33)=|(1,2),(1,1)|=1-2=-1`
`:.a_(31)A_(31)+a_(32)A_(32)+a_(33)A_(33)`
`=2(7)+4(-2)+7(-1)`
`=14-8-7=-1`
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