-
uptowngirl92
- Master | Next Rank: 500 Posts
- Posts: 447
- Joined: Sun Apr 19, 2009 9:08 pm
- Location: Kolkata,India
- Thanked: 7 times
- GMAT Score:670
Modulus question.
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
mehravikas
- Legendary Member
- Posts: 1161
- Joined: Mon May 12, 2008 2:52 am
- Location: Sydney
- Thanked: 23 times
- Followed by:1 members
|x-1| < 1
so 0<|x-1|<1
hence 0<x<2
we need to find out if x is between this range exclusively
1) (x-1)^2 <=1
x^2-2x <=0
x(x-2)<=0
testing some numbers we quickly find that this range fits the bill of 0 to 2 so 1 is suff
2) x^2-1>0
(x+1)(x-1)>0
can have +ve * +ve --> x>-1, x>1 --> x>1
or -ve * -ve --> x<-1, x<1 --> x<-1
either of these 2 answers lie both inside AND outside the desired range so insuff
Ans ought to be A
so 0<|x-1|<1
hence 0<x<2
we need to find out if x is between this range exclusively
1) (x-1)^2 <=1
x^2-2x <=0
x(x-2)<=0
testing some numbers we quickly find that this range fits the bill of 0 to 2 so 1 is suff
2) x^2-1>0
(x+1)(x-1)>0
can have +ve * +ve --> x>-1, x>1 --> x>1
or -ve * -ve --> x<-1, x<1 --> x<-1
either of these 2 answers lie both inside AND outside the desired range so insuff
Ans ought to be A
-
mehravikas
- Legendary Member
- Posts: 1161
- Joined: Mon May 12, 2008 2:52 am
- Location: Sydney
- Thanked: 23 times
- Followed by:1 members
From the question stem - 0 < x < 2
From statement 1 - x could be 0 or less than zero
x could be 2 or less than 2
Then how is 'A' sufficient? what if x = 0 as 0 <= 0 is true but 0 < 0 is false.
From statement 1 - x could be 0 or less than zero
x could be 2 or less than 2
Then how is 'A' sufficient? what if x = 0 as 0 <= 0 is true but 0 < 0 is false.
m&m wrote:|x-1| < 1
so 0<|x-1|<1
hence 0<x<2
we need to find out if x is between this range exclusively
1) (x-1)^2 <=1
x^2-2x <=0
x(x-2)<=0
testing some numbers we quickly find that this range fits the bill of 0 to 2 so 1 is suff
2) x^2-1>0
(x+1)(x-1)>0
can have +ve * +ve --> x>-1, x>1 --> x>1
or -ve * -ve --> x<-1, x<1 --> x<-1
either of these 2 answers lie both inside AND outside the desired range so insuff
Ans ought to be A
-
mehravikas
- Legendary Member
- Posts: 1161
- Joined: Mon May 12, 2008 2:52 am
- Location: Sydney
- Thanked: 23 times
- Followed by:1 members
