To solve the problem (assuming the common constraint (a+b+c=1) for positive reals (a,b,c) and finding the minimum of ((\frac{1}{a}-1)(\frac{1}{b}-1)(\frac{1}{c}-1))):
Step 1: Rewrite the expression
For (a+b+c=1):
[
\frac{1}{a}-1 = \frac{1-a}{a} = \frac{b+c}{a}
]
Similarly:
[
\frac{1}{b}-1=\frac{a+c}{b}, \quad \frac{1}{c}-1=\frac{a+b}{c}
]
The product becomes:
[
\frac{(b+c)(a+c)(a+b)}{abc}
]
Step 2: Apply AM ≥ GM
By AM ≥ GM:
[
b+c \geq 2\sqrt{bc}, \quad a+c \geq 2\sqrt{ac}, \quad a+b \geq 2\sqrt{ab}
]
Multiply these inequalities:
[
(b+c)(a+c)(a+b) \geq 8\sqrt{bc \cdot ac \cdot ab} = 8abc
]
Step 3: Simplify
[
\frac{(b+c)(a+c)(a+b)}{abc} \geq 8
]
Equality holds when (a=b=c=\frac{1}{3}).
Answer: (\boxed{8})

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