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If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x

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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 13 May 2015, 07:14
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ranaazad wrote:
Bunuel wrote:
Hussain15 wrote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x

Will really appreciate if answer is supported by explanation.


\(x\neq{0}\), is \(|x|<1\)? Which means is \(-1<x<1\)? (\(x\neq{0}\))

(1) \(\frac{x}{|x|}< x\)
Two cases:
A. \(x<0\) --> \(\frac{x}{-x}<x\) --> \(-1<x\). But remember that \(x<0\), so \(-1<x<0\)

B. \(x>0\) --> \(\frac{x}{x}<x\) --> \(1<x\).

Two ranges \(-1<x<0\) or \(x>1\). Which says that \(x\) either in the first range or in the second. Not sufficient to answer whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(3\))

Second approach: look at the fraction \(\frac{x}{|x|}\) it can take only two values:
1 for \(x>0\) --> so we would have: \(1<x\);
Or -1 for \(x<0\) --> so we would have: \(-1<x\) and as we considering the range for which \(x<0\) then completer range would be: \(-1<x<0\).

The same two ranges: \(-1<x<0\) or \(x>1\).

(2) \(|x| > x\). Well this basically tells that \(x\) is negative, as if x were positive or zero then \(|x|\) would be equal to \(x\). Only one range: \(x<0\), but still insufficient to say whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(-10\))

Or two cases again:
\(x<0\)--> \(-x>x\)--> \(x<0\).
\(x>0\) --> \(x>x\): never correct.


(1)+(2) Intersection of the ranges from (1) and (2) is the range \(-1<x<0\) (\(x<0\) (from 2) and \(-1<x<0\) or \(x>1\) (from 1), hence \(-1<x<0\)). Every \(x\) from this range is definitely in the range \(-1<x<1\). Sufficient.

Answer: C.



Thanks for your nice explanations. I am not clear on one issue though. As we can multiply an inequality by a variable only if we know its sign, how can we multiply both side of an inequality by an absolute value? Would you please explain..


An absolute value of a number cannot be negative (it's 0 or positive), and since we are given that x is not 0, then |x| is positive only.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 09 Mar 2016, 00:08
1
Quote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x



Given : x is NOT equal to zero

Question : Is |x| < 1?

Statement 1: x/|x|< x

Case 1: If x <0, x/|x| = -1 i.e. x/|x|< x can be rewritten as -1< x i.e. -1< x < 0 Giving answer to the question as YES
Case 2: If x >0, x/|x| = +1 i.e. x/|x|< x can be rewritten as 1< x i.e. 1< x Giving answer to the question as NO
NOT SUFFICIENT

Statement 2: |x| > x
|x| can be greater than x only if x is Negative because in all other cases both will be equal
i.e. x < 0 but x may be -0.5 Giving answer to the question as YES and x may be -1.5 Giving answer to the question as NO. Hence,
NOT SUFFICIENT

Combining the two statements
Combining -1< x < 0 and 1< x and x < 0

we get, only -1< x < 0 Giving answer to the question as YES. Hence,
SUFFICIENT

Answer: option C
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 28 Aug 2010, 10:29
Thanks Bunuel, It's terrific explanation...too detail..concept is now crystal clear!!
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 07 Jan 2012, 20:50
1
Hi Bunuel - Firstly thanks for the wonderful collection and the explanation you provided in the word format.

1. In this kind of inequalities involving ‘mod’ values is it ever advisable to first square both side and then proceed ? I saw somewhere this approach was quite fast to solve the problem.
2. In this specific example as it involves negative & decimal , squaring and multiplying makes things erroneous .

Please suggest if there has any general rule/comment on this?

Thanks,
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 19 Jan 2012, 08:29
Bunuel wrote:
udaymathapati wrote:
Hi Bunuel,
Thanks for detail explanation. I am finding it difficult only last intersection part. Can you explain it further. My doubut is...If we combine "-1<x<0" or "x>1" these two inequalities, how come range for x fall betweeen -1<x<1 since x>1 is area which will not fit into this equation. Can you explain?


Range from (1): -----(-1)----(0)----(1)---- \(-1<x<0\) or \(x>1\), green area;

Range from (2): -----(-1)----(0)----(1)---- \(x<0\), blue area;

From (1) and (2): ----(-1)----(0)----(1)---- \(-1<x<0\), common range of \(x\) from (1) and (2) (intersection of ranges from (1) and (2)), red area.

Hope it's clear.



Hi Bunuel...I still didnot got it..red area says -1<x<0 but we need that -1<x<1
Please explain
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 11 Apr 2012, 13:43
bunuel,

i had a slightly slightly different method for statement 1. Do you mind letting me know if the steps I took are OK?

also, what level question is this? My test is coming up soon and I've done all the OG and quant review 2nd edition problems. I wonder if going through these two samurai guides PS/DS would be the best use of my time in the final month and half.


(1).
x/|x| < x
before even going to x<0 and x>0, i knew that |x| is positive, so I multiplied it across
x < x*|x|

case x < 0

divide both sides by x, inequality must flip because x is negative
1 > |x| <-- this says YES to what we asked for


case x > 0

again, divide both sides by x, inequality won't flip
1 < |x| <-- this says NO

insufficient

(2). clearly says x has to be negative, therefore using (1) and (2) it is sufficient.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 15 Apr 2012, 23:18
arjuntomar wrote:
Hi Bunuel,

Sorry to bring this up after the question has been convincingly answered but I have a small doubt:

In the first statement, x/(mod x), while considering the possibility x<0, you write x > x/(-x) and conclude that x>-1.
But shouldn't the sign of inequality flip in this case as you are dividing by a negative number? What I mean to say is that shouldn't

x > x/(-x) give us x<-1?

Sorry in advance if I am making an illogical conclusion but if you could clarify, I would appreciate it very much. Thanks.


From \(x>\frac{x}{-x}\) we don't dividing the inequality by some negative number, all we do is just reduce fraction. Since \(\frac{x}{-x}=-1\) (the same way as \(\frac{2}{-2}=-1\)) then from \(x>\frac{x}{-x}\) we have that \(x>-1\).

Hope it's clear.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 09 Jun 2012, 08:52
1
Bunuel wrote:
Hussain15 wrote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x

Will really appreciate if answer is supported by explanation.


\(x\neq{0}\), is \(|x|<1\)? Which means is \(-1<x<1\)? (\(x\neq{0}\))

(1) \(\frac{x}{|x|}< x\)
Two cases:
A. \(x<0\) --> \(\frac{x}{-x}<x\) --> \(-1<x\). But remember that \(x<0\), so \(-1<x<0\)

B. \(x>0\) --> \(\frac{x}{x}<x\) --> \(1<x\).

Two ranges \(-1<x<0\) or \(x>1\). Which says that \(x\) either in the first range or in the second. Not sufficient to answer whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(3\))

Second approach: look at the fraction \(\frac{x}{|x|}\) it can take only two values:
1 for \(x>0\) --> so we would have: \(1<x\);
Or -1 for \(x<0\) --> so we would have: \(-1<x\) and as we considering the range for which \(x<0\) then completer range would be: \(-1<x<0\).

The same two ranges: \(-1<x<0\) or \(x>1\).

(2) \(|x| > x\). Well this basically tells that \(x\) is negative, as if x were positive or zero then \(|x|\) would be equal to \(x\). Only one range: \(x<0\), but still insufficient to say whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(-10\))

Or two cases again:
\(x<0\)--> \(-x>x\)--> \(x<0\).
\(x>0\) --> \(x>x\): never correct.


(1)+(2) Intersection of the ranges from (1) and (2) is the range \(-1<x<0\) (\(x<0\) (from 2) and \(-1<x<0\) or \(x>1\) (from 1), hence \(-1<x<0\)). Every \(x\) from this range is definitely in the range \(-1<x<1\). Sufficient.

Answer: C.



Hey Bunuel,

Love your answers. But I want to suggest another method that is giving me some trouble when combining statesment (1) & (2)

1) \(\frac{x}{|x|}< x\)
2) \(x<|x|\)

Since \(0<|x|\) (x cannot equal 0), then we can rewrite statement 2, \(x<|x|\) as \(\frac{x}{|x|}< 1\).

We then subtract statment (1) and (2) as

1) \(\frac{x}{|x|}-\frac{x}{|x|}< x-1\) to get \(0< x-1\) or \(1<x\) showing that x is outside the boundary of \(-1<x<1\) and making the combined statements suffient. But \(1<x\), the derived statement of (1) and (2), contradicts statement (2), which claims that \(0<x\). What am I doing wrong?

Thank you!
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If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 01 Jan 2015, 21:46
Hi,

There are a handful of Number Property rules in this DS question that you can find by either TESTing VALUES or taking lots of notes.

We're told that X cannot = 0. We're asked if |X| < 1. This is a YES/NO question.

Fact 1: X/|X| < X

This inequality requires a thorough examination of the possibilities.

X CANNOT = 1 since 1/|1| is NOT < 1

X can be ANY number > 1 though

If X = 2....
2/|2| < 2
And the answer to the question is NO.

X CANNOT be a positive fraction...

If X = 1/2
(1/2)/|1/2| = 1 which is NOT < 1/2

X could be ANY negative fraction though

If X = -1/2
(-1/2)/|-1/2| = -1 which IS < -1/2
And the answer to the question is YES.

X CANNOT be -1 since -1/|-1| is NOT < -1

X CANNOT be < -1...

X = -2
(-2)/|-2| = -1 which is NOT < -2

According to all of this data, the possibilities are X > 1 or -1 < X < 0
Fact 1 is INSUFFICIENT

Fact 2: |X|> X

Here, we know that X can be ANY negative, but CANNOT be positive.

If X = -1/2 then the answer to the question is YES (we did the work already in Fact 1)
If X = -2 then the answer to the question is NO
Fact 2 is INSUFFICIENT

Combining Facts, we have...
X > 1 or -1 < X < 0
AND
X MUST be negative

The ONLY possibilities that fit BOTH Facts ARE negative fractions. Thus the answer to the question will be ALWAYS YES.
Combined, SUFFICIENT

Final Answer:

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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 13 May 2015, 06:19
Bunuel wrote:
Hussain15 wrote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x

Will really appreciate if answer is supported by explanation.


\(x\neq{0}\), is \(|x|<1\)? Which means is \(-1<x<1\)? (\(x\neq{0}\))

(1) \(\frac{x}{|x|}< x\)
Two cases:
A. \(x<0\) --> \(\frac{x}{-x}<x\) --> \(-1<x\). But remember that \(x<0\), so \(-1<x<0\)

B. \(x>0\) --> \(\frac{x}{x}<x\) --> \(1<x\).

Two ranges \(-1<x<0\) or \(x>1\). Which says that \(x\) either in the first range or in the second. Not sufficient to answer whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(3\))

Second approach: look at the fraction \(\frac{x}{|x|}\) it can take only two values:
1 for \(x>0\) --> so we would have: \(1<x\);
Or -1 for \(x<0\) --> so we would have: \(-1<x\) and as we considering the range for which \(x<0\) then completer range would be: \(-1<x<0\).

The same two ranges: \(-1<x<0\) or \(x>1\).

(2) \(|x| > x\). Well this basically tells that \(x\) is negative, as if x were positive or zero then \(|x|\) would be equal to \(x\). Only one range: \(x<0\), but still insufficient to say whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(-10\))

Or two cases again:
\(x<0\)--> \(-x>x\)--> \(x<0\).
\(x>0\) --> \(x>x\): never correct.


(1)+(2) Intersection of the ranges from (1) and (2) is the range \(-1<x<0\) (\(x<0\) (from 2) and \(-1<x<0\) or \(x>1\) (from 1), hence \(-1<x<0\)). Every \(x\) from this range is definitely in the range \(-1<x<1\). Sufficient.

Answer: C.



Thanks for your nice explanations. I am not clear on one issue though. As we can multiply an inequality by a variable only if we know its sign, how can we multiply both side of an inequality by an absolute value? Would you please explain..
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x| < x  [#permalink]

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New post 07 Jun 2015, 15:19
Hi All,

This DS question is built around some interesting Number Properties and patterns. If you can spot those patterns, then solving this problem should take considerably less time. This also looks like a question that can be beaten by TESTing VALUES.

We're told that X CANNOT = 0. We're asked if |X| < 1. This is a YES/NO question.

Fact 1: X/|X| < X

Before TESTing VALUES, I want to note a pattern in this inequality:

X/|X| will either equal 1 (if X is positive) OR -1 (if X is negative). This will save us some time when it comes to TESTing VALUES, since there are many values of X that will NOT fit this information.

If X = 2, then the answer to the question is NO.

X cannot be 1, any positive fraction, 0, or any negative integer…..

So what's left to TEST….?

If X = -1/2, then the answer to the question is YES.
Fact 1 is INSUFFICIENT

Fact 2: |X| > X

This tells us that X CANNOT be positive or 0.

If X = -1, then the answer to the question is NO.
If X = -1/2, then the answer to the question is YES.
Fact 2 is INSUFFICIENT

Combined, we have deal with the "overlapping restrictions" that we noted in the two Facts:
X cannot be….anything positive, 0, or any negative integer.
X can ONLY BE negative fractions between 0 and -1.
ALL of those answers (e.g. -1/2, -.4, etc.) lead to a YES answer.
Combined SUFFICIENT.

Final Answer:

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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 05 Jul 2015, 15:45
Bunuel wrote:
Hussain15 wrote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x

Will really appreciate if answer is supported by explanation.


\(x\neq{0}\), is \(|x|<1\)? Which means is \(-1<x<1\)? (\(x\neq{0}\))

(1) \(\frac{x}{|x|}< x\)
Two cases:
A. \(x<0\) --> \(\frac{x}{-x}<x\) --> \(-1<x\). But remember that \(x<0\), so \(-1<x<0\)

B. \(x>0\) --> \(\frac{x}{x}<x\) --> \(1<x\).

Two ranges \(-1<x<0\) or \(x>1\). Which says that \(x\) either in the first range or in the second. Not sufficient to answer whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(3\))

Second approach: look at the fraction \(\frac{x}{|x|}\) it can take only two values:
1 for \(x>0\) --> so we would have: \(1<x\);
Or -1 for \(x<0\) --> so we would have: \(-1<x\) and as we considering the range for which \(x<0\) then completer range would be: \(-1<x<0\).

The same two ranges: \(-1<x<0\) or \(x>1\).

(2) \(|x| > x\). Well this basically tells that \(x\) is negative, as if x were positive or zero then \(|x|\) would be equal to \(x\). Only one range: \(x<0\), but still insufficient to say whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(-10\))

Or two cases again:
\(x<0\)--> \(-x>x\)--> \(x<0\).
\(x>0\) --> \(x>x\): never correct.


(1)+(2) Intersection of the ranges from (1) and (2) is the range \(-1<x<0\) (\(x<0\) (from 2) and \(-1<x<0\) or \(x>1\) (from 1), hence \(-1<x<0\)). Every \(x\) from this range is definitely in the range \(-1<x<1\). Sufficient.

Answer: C.



I did mine a little differently.

If x ≠ 0, is |x| < 1?


Means: Is -1 < x < 1?

(1) \(\frac{x}{|x|}< x\)

x < |x|*x
If x is positive, then: \(\frac{x}{x} < |x|\) which is the same as \(1 < |x|\)
This means that \(-1 > x > 1\)

If x is negative, then: \(\frac{x}{x} > |x|\) which is the same as \(1 > |x|\)
This means that \(-1 < x < 1\) (we switch the direction of < to > because we divided by -1 to put |x| by itself).

These two answers are inconsistent: x is both less than 1 and greater than 1. So, insufficient.

(2) \(|x| > x\)
This means that x is negative since the negative value of something is always less than the absolute value of something; whereas, a positive or 0 value of something is equal to its absolute value.

If x is equal to a negative value less than -1, then it's within the range -1 < x < 1. But, if x is equal to a large negative value, |x| can be out of range, for example, x = -1,000. Therefore, (2) is insufficient.

(1) + (2)
|x| > x and |x| > 1
x is negative, and we know that x < -1. So, pick an arbitrary value less than -1, say, -5.
Plug it into equation (1): \(\frac{-5}{|-5|} < -5\). Is \(-1< -5\)? False. x does not refer to values < -1.

|x| > x and |x| < 1
x is negative, and we know that x > -1. Therefore, \(-1 < x < 0\).
Pick an arbitrary value between -1 and 0, non-inclusive, say, -0.5.
Plug it into equation (1): \(\frac{-0.5}{|-0.5|} < -0.5\). Is \(-1 < -0.5\)? Yes, this works. Sufficient.

Answer C.
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Re: If x is not equal to 0, is |x| less than 1?  [#permalink]

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New post 17 Nov 2015, 09:24
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

If x is not equal to 0, is |x| less than 1?

(1) x/|x| < x
(2) |x| > x

If the range of the condition falls into that of the condition in terms of inequalities, the condition is sufficient.

There is 1 variable in the original condition, and there are 2 equations provided by the 2 conditions, so there is high chance (D) will be our answer.
For condition 1, if x>0, x/|x|<x --> x/x<x --> 1<x, then 1<x
if x<0, x/|x|<x --> x/-x<x --> -1<x, then -1<x<0. Therefore this condition is insufficient because this range does not fall into that of the question.
For condition 2, |x|>x --> x<0. This is insufficient for the same reason.
Looking at them together, however, -1<x<0 falls into the range of the question, so this is sufficient, and the answer becomes (C).

For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 08 Mar 2016, 16:30
Hi Bunuel,

For the A, how did you assume that remember that x<0

Thanks
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 08 Mar 2016, 22:48
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 15 Oct 2017, 13:02
For (1), wouldn't x<0 give you:

-x/x < -x
-1 < -x
1 > x?

When I plug in numbers for that, it doesn't work, but I don't see how we get x/-x < x when plugging in x<0?


Bunuel wrote:
Hussain15 wrote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x

Will really appreciate if answer is supported by explanation.


\(x\neq{0}\), is \(|x|<1\)? Which means is \(-1<x<1\)? (\(x\neq{0}\))

(1) \(\frac{x}{|x|}< x\)
Two cases:
A. \(x<0\) --> \(\frac{x}{-x}<x\) --> \(-1<x\). But remember that \(x<0\), so \(-1<x<0\)

B. \(x>0\) --> \(\frac{x}{x}<x\) --> \(1<x\).

Two ranges \(-1<x<0\) or \(x>1\). Which says that \(x\) either in the first range or in the second. Not sufficient to answer whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(3\))

Second approach: look at the fraction \(\frac{x}{|x|}\) it can take only two values:
1 for \(x>0\) --> so we would have: \(1<x\);
Or -1 for \(x<0\) --> so we would have: \(-1<x\) and as we considering the range for which \(x<0\) then completer range would be: \(-1<x<0\).

The same two ranges: \(-1<x<0\) or \(x>1\).

(2) \(|x| > x\). Well this basically tells that \(x\) is negative, as if x were positive or zero then \(|x|\) would be equal to \(x\). Only one range: \(x<0\), but still insufficient to say whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(-10\))

Or two cases again:
\(x<0\)--> \(-x>x\)--> \(x<0\).
\(x>0\) --> \(x>x\): never correct.


(1)+(2) Intersection of the ranges from (1) and (2) is the range \(-1<x<0\) (\(x<0\) (from 2) and \(-1<x<0\) or \(x>1\) (from 1), hence \(-1<x<0\)). Every \(x\) from this range is definitely in the range \(-1<x<1\). Sufficient.

Answer: C.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 15 Oct 2017, 20:17
cgarmestani wrote:
For (1), wouldn't x<0 give you:

-x/x < -x
-1 < -x
1 > x?

When I plug in numbers for that, it doesn't work, but I don't see how we get x/-x < x when plugging in x<0?


Bunuel wrote:
Hussain15 wrote:
If x is not equal to 0, is |x| less than 1?

(1) x/|x|< x

(2) |x| > x

Will really appreciate if answer is supported by explanation.


\(x\neq{0}\), is \(|x|<1\)? Which means is \(-1<x<1\)? (\(x\neq{0}\))

(1) \(\frac{x}{|x|}< x\)
Two cases:
A. \(x<0\) --> \(\frac{x}{-x}<x\) --> \(-1<x\). But remember that \(x<0\), so \(-1<x<0\)

B. \(x>0\) --> \(\frac{x}{x}<x\) --> \(1<x\).

Two ranges \(-1<x<0\) or \(x>1\). Which says that \(x\) either in the first range or in the second. Not sufficient to answer whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(3\))

Second approach: look at the fraction \(\frac{x}{|x|}\) it can take only two values:
1 for \(x>0\) --> so we would have: \(1<x\);
Or -1 for \(x<0\) --> so we would have: \(-1<x\) and as we considering the range for which \(x<0\) then completer range would be: \(-1<x<0\).

The same two ranges: \(-1<x<0\) or \(x>1\).

(2) \(|x| > x\). Well this basically tells that \(x\) is negative, as if x were positive or zero then \(|x|\) would be equal to \(x\). Only one range: \(x<0\), but still insufficient to say whether \(-1<x<1\). (For instance \(x\) can be \(-0.5\) or \(-10\))

Or two cases again:
\(x<0\)--> \(-x>x\)--> \(x<0\).
\(x>0\) --> \(x>x\): never correct.


(1)+(2) Intersection of the ranges from (1) and (2) is the range \(-1<x<0\) (\(x<0\) (from 2) and \(-1<x<0\) or \(x>1\) (from 1), hence \(-1<x<0\)). Every \(x\) from this range is definitely in the range \(-1<x<1\). Sufficient.

Answer: C.


If x < 0, then |x| = -x.

Substitute |x| by -x in x/|x|< x to get x/(-x) < x and then to get -1 < x. Since we consider the range when x < 0, then -1 < x < 0.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 29 Nov 2017, 06:09
Bunuel wrote:
udaymathapati wrote:
Hi Bunuel,
Thanks for detail explanation. I am finding it difficult only last intersection part. Can you explain it further. My doubut is...If we combine "-1<x<0" or "x>1" these two inequalities, how come range for x fall betweeen -1<x<1 since x>1 is area which will not fit into this equation. Can you explain?


Range from (1): -----(-1)----(0)----(1)---- \(-1<x<0\) or \(x>1\), green area;

Range from (2): -----(-1)----(0)----(1)---- \(x<0\), blue area;

From (1) and (2): ----(-1)----(0)----(1)---- \(-1<x<0\), common range of \(x\) from (1) and (2) (intersection of ranges from (1) and (2)), red area.

Hope it's clear.


the red zone indicates that the range is -1<x<0 , how do we arrive at -1<x<1?
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x  [#permalink]

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New post 29 Nov 2017, 06:22
yousufkhan wrote:
Bunuel wrote:
udaymathapati wrote:
Hi Bunuel,
Thanks for detail explanation. I am finding it difficult only last intersection part. Can you explain it further. My doubut is...If we combine "-1<x<0" or "x>1" these two inequalities, how come range for x fall betweeen -1<x<1 since x>1 is area which will not fit into this equation. Can you explain?


Range from (1): -----(-1)----(0)----(1)---- \(-1<x<0\) or \(x>1\), green area;

Range from (2): -----(-1)----(0)----(1)---- \(x<0\), blue area;

From (1) and (2): ----(-1)----(0)----(1)---- \(-1<x<0\), common range of \(x\) from (1) and (2) (intersection of ranges from (1) and (2)), red area.

Hope it's clear.


the red zone indicates that the range is -1<x<0 , how do we arrive at -1<x<1?


The question asks whether \(-1<x<1\) is true. We got that \(-1<x<0\). Any, x from \(-1<x<0\) IS in the range from -1 to 1, so we have an YES answer to the question.
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Re: If x is not equal to 0, is |x| less than 1? (1) x/|x|< x (2) |x| > x   [#permalink] 29 Nov 2017, 06:22

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