|x^3|< 64 : Quantitative Comparison Questions

|x^3|< 64

Author

Message

TAGS:

Founder

Joined: 18 Apr 2015

Posts: 6647

Followers: 107

Kudos [?]: 1275 [0], given: 6017

|x^3|< 64 [#permalink]

08 Aug 2018, 16:12

Expert's post

00:00

Question Stats:

59% (00:45) correct

40% (00:41) wrong

based on 54 sessions

\(|x^3|< 64\)

Quantity A	Quantity B
\(-x\)	\(-\|x\|\)

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.

Kudos for R.A.E

[Reveal] Spoiler: OA

_________________

Get the 2 FREE GREPrepclub Tests

GRE Instructor

Joined: 10 Apr 2015

Posts: 1802

Followers: 58

Kudos [?]: 1686 [1] , given: 8

Re: |x^3|< 64 [#permalink]

09 Aug 2018, 12:55

This post received
KUDOS

Expert's post

Carcass wrote:

\(|x^3|< 64\)

Quantity A	Quantity B
-x	-\|x\|

Let's test some possible values of x

CASE 1
Since |0³| < 64, x COULD equal 0
We get:
Quantity A: -0
Quantity B: -|0|

Evaluate to get:
Quantity A: 0
Quantity B: 0
In this case, the two quantities are EQUAL

CASE 2
Since |(-1)³| < 64, x COULD equal -1
We get:
Quantity A: -(-1)
Quantity B: -|-1|

Evaluate to get:
Quantity A: 1
Quantity B: -1
In this case, Quantity A IS GREATER

Answer: D

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com

Sign up for my free GRE Question of the Day emails

Manager

Joined: 06 Jun 2018

Posts: 94

Followers: 0

Kudos [?]: 59 [0], given: 0

Re: |x^3|< 64 [#permalink]

09 Aug 2018, 15:47

Carcass wrote:

\(|x^3|< 64\)

Quantity A	Quantity B
-x	-\|x\|

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.

Kudos for R.A.E

30 sec approach :

It's impossible to determine the sign of a variable that keeps inside the absolute value sign. X could be positive or negative. U will get know definite value of x.

The best answer is D.

GRE Forum Moderator

Joined: 31 Jul 2018

Posts: 32

GPA: 3.07

Followers: 0

Kudos [?]: 12 [0], given: 3

Re: |x^3|< 64 [#permalink]

10 Aug 2018, 03:38

I selected option B because -|x| = -x.

How is it the D? I still do not understand. Could anyone further explain both question and answer?

Thank you.
_________________

I am doing it.

GRE Instructor

Joined: 10 Apr 2015

Posts: 1802

Followers: 58

Kudos [?]: 1686 [1] , given: 8

Re: |x^3|< 64 [#permalink]

10 Aug 2018, 05:07

This post received
KUDOS

Expert's post

ajbozdar wrote:

I selected option B because -|x| = -x.

How is it the D? I still do not understand. Could anyone further explain both question and answer?

Thank you.

It is not always the case that -|x| = -x

If x is a POSITIVE number, then -|x| = -x
For example, if x = 2, we get: -|2| = -2
Simplify to get: -2 = -2

However, if x is a NEGATIVE number, then it is NOT the case that -|x| = -x
For example, if x = -3, we get: -|-3| = -(-3)
Simplify to get: -3 = 3, which is NOT TRUE

Does that help?

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com

Sign up for my free GRE Question of the Day emails

GRE Forum Moderator

Joined: 31 Jul 2018

Posts: 32

GPA: 3.07

Followers: 0

Kudos [?]: 12 [0], given: 3

Re: |x^3|< 64 [#permalink]

10 Aug 2018, 06:25

GreenlightTestPrep wrote:

However, if x is a NEGATIVE number, then it is NOT the case that -|x| = -x
For example, if x = -3, we get: -|-3| = -(-3)
Simplify to get: -3 = 3, which is NOT TRUE

Does that help?

I have learnt that any negative number under mod becomes positive.

If so, -|-3| = -(3) i.e. = -3

Did I learn the wrong concept of absolute value?
_________________

I am doing it.

GRE Instructor

Joined: 10 Apr 2015

Posts: 1802

Followers: 58

Kudos [?]: 1686 [1] , given: 8

Re: |x^3|< 64 [#permalink]

10 Aug 2018, 08:13

This post received
KUDOS

Expert's post

ajbozdar wrote:

GreenlightTestPrep wrote:

However, if x is a NEGATIVE number, then it is NOT the case that -|x| = -x
For example, if x = -3, we get: -|-3| = -(-3)
Simplify to get: -3 = 3, which is NOT TRUE

Does that help?

I have learnt that any negative number under mod becomes positive.

If so, -|-3| = -(3) i.e. = -3

Did I learn the wrong concept of absolute value?

You learned the correct concept.
In my solution, you'l see that I also state that -|-3| = -(3) = -3

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com

Sign up for my free GRE Question of the Day emails

Founder

Joined: 18 Apr 2015

Posts: 6647

Followers: 107

Kudos [?]: 1275 [0], given: 6017

Re: |x^3|< 64 [#permalink]

21 Oct 2018, 00:39

Expert's post

Yes.

Regards
_________________

Get the 2 FREE GREPrepclub Tests

Manager

Joined: 23 Oct 2018

Posts: 57

Followers: 0

Kudos [?]: 0 [0], given: 0

Re: |x^3|< 64 [#permalink]

23 Oct 2018, 08:43

is it possible to have negative sign in absolut value

Re: |x^3|< 64 [#permalink] 23 Oct 2018, 08:43

|x^3|< 64

Main navigation

Partners

GRE Resources

GRE® is a registered trademark of the Education Testing Services® (ETS ®). GRE Prep Club's website has not been reviewed or endorsed by ETS

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

|x^3|< 64

|x^3|< 64

Main navigation

Partners

GRE Resources