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LetA = [a(ij)](3xx 3) If tr is arithmeti...

Let`A = [a_(ij)]_(3xx 3)` If tr is arithmetic mean of elements of rth row and `a_(ij )+ a_( jk) + a_(ki)=0` hold for all `1 le i, j, k le 3.` ` sum_(1lei) sum_(jle3) a _(ij)` is not equal to

A

`t_(1) + t_(2) + t_(3)`

B

zero

C

`(det(A))^(2)`

D

`t_(1) t_(2)t_(3)`

Text Solution

Verified by Experts

The correct Answer is:
D
`therefore A = [[a_(11) , a_(12),a_(13)],[a_(21),a_(22), a_(23) ],[a_(31), a_(32),a_(33)]]`
`rArr t_(1) = (a_(11) + a_(12)+a_(23))/3 = 0, [because a_(ij) + a_(jk) + a_(ki)=0]`
`t_(2) = (a_(21) + a_(22) + a_(23))/3 = 0`
and `t_(3) = (a_(31) + a_(32) + a_(33))/3 = 0`
`sum _(1lei), sum _(jle 3) a_(ij) =3 (t_(1) + t_(2) + t_(3)) = 0 = t_(1) + t_(2) + t_(3) `
`ne t_(1) t_(2) t_(3) " "[because t_(1) = 0 , t_(2 ) = 0, t_(3) = 0]`
and det ` A = [[a_(11) , a_(12),a_(13)],[a_(21),a_(22), a_(23) ],[a_(31), a_(32),a_(33)]]`
Applying `C_(1)rarr C_(1)+ C_(2) +C_(3),` we get
` = [[0 , a_(12),a_(13)],[0,a_(22), a_(23) ],[0, a_(32),a_(33)]]=0`
`therefore (detA)^(2) = 0`
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