IMO C
question : IS -1<x<1
s1) solving for x can be 3 or 1/3
s2) x is not 3
combining x is 1/3 suff
OA
Absolutely unequal - 2
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Source: Beat The GMAT — Data Sufficiency |
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thephoenix
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Stem
Is -1<x<1
Statement one
Each |x| can either have value x or -x
So |x+1| can be +ve or -ve
Same way |x-1| can be +ve or -ve
That leaves us with 2 cases
x+1 = 2(x-1)
which gives x=3
x+1 = -2(x-1)
which gives us x =-1/3
Hence Insuff
Statement two
Implies x is not 3
Combined
Since x is not 3 it has to be -3 which is within -1<x<1
Hence Suff
Is -1<x<1
Statement one
Each |x| can either have value x or -x
So |x+1| can be +ve or -ve
Same way |x-1| can be +ve or -ve
That leaves us with 2 cases
x+1 = 2(x-1)
which gives x=3
x+1 = -2(x-1)
which gives us x =-1/3
Hence Insuff
Statement two
Implies x is not 3
Combined
Since x is not 3 it has to be -3 which is within -1<x<1
Hence Suff
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