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If alpha, beta. gamma are the roots of x...

If `alpha, beta. gamma` are the roots of `x^3 + px^2 + q = 0,` where `q=0,` then `Delta=|(1/alpha,1/beta,1/gamma),(1/beta,1/gamma,1/alpha),(1/gamma,1/alpha,1/beta)|` equals

A

`alpha beta gamma`

B

`alpha +beta + gamma `

C

`0`

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
C

`(d)` We have `betaalpha+gammaalpha+alphabeta=0`
`Delta=(1)/(alpha^(3)beta^(3)gamma^(3))|{:(betagamma,gammaalpha,alphabeta),(gammaalpha,alphabeta,betagamma),(alphabeta,betagamma,gammaalpha):}|`
`=(1)/(alpha^(3)beta^(3)gamma^(3))|{:(betagamma+gammaalpha+alphabeta,gammaalpha,alphabeta),(gammaalpha+alphabeta+betagamma,alphabeta,betagamma),(alphabeta+betagamma+gammaalpha,betagamma,gammaalpha):}|` [using `C_(1)toC_(1)+C_(2)+C_(3)`]
`=(1)/(alpha^(3)beta^(3)gamma^(3))|{:(0,gammaalpha,alphabeta),(0,alphabeta,betagamma),(0,betagamma,gammaalpha):}|=0` [all zero property].
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