the eq. can be written as
(1/a-1)(1/b-1)(1/c-1)
let a+b+c=x
therefore
= (x/a-1)(x/b-1)(x/c-1)
as x=1 (given)
on simplifying it gives
(a+b)(a+c)(b+c)/abc RIGHT!!............................1
NOW
we know
A.M. >=G.M
(a+b)/2>=(ab)^1/2
similarly for
(b+c) and (a+c)
multiplying them we have,
(a+b)(a+c)(b+c)>= 8abc
which can be written as
(a+b)(a+c)(b+c)/abc>=8
from (1)
we get the desired result.....
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