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.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

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

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

If \(|x| > 3\) , which of the following must be true?

I. \(x > 3\)

II. \(x^2 > 9\)

III. \(|x - 1| > 2\)

A. I only B. II only C. I and II only D. II and III only E. I, II, and III

I don't understand well III. \(|x - 1| > 2\) is equivalent to \(x > 3\) or \(x < -1\). The last inequality (\(x < -1\) ) includes integers -2 and -3, integers that are not included in one of the original inequalities ( \(x < -3\) ). How could III be true?

If some numbers confuse you, don't fixate on them. Go ahead and take some other easier examples. Let's keep the wording of the question same but make it simple.

If n < 6, which of the following must be true?

I.

II.

III. n < 8

Can we say that III must be true? Yes! If n is less than 6 then obviously it is less than 8 too. If n is less than 6, it will take values such as -20, 2, 5 etc. All of these values will be less than 8 too.

Values 6 and 7 are immaterial because n cannot take these values. You are given that n is less than 6 so you only need to worry about values that n CAN take. Those should satisfy n < 8.

Similarly, your question says that x > 3 or x < -3

Then we can say that x > 3 or x < -1. All values that will be less than -3 will be less than -1 too.

Re: If |x| > 3 , which of the following must be true? [#permalink]

Show Tags

13 Aug 2013, 12:40

What if x = -2 that is < -1 but > than -3 so IIImust be out?no

Zarrolou wrote:

Archit143 wrote:

I too have the same doubt...can anyone address the query

Archit

The question asks is \(x>3\) or \(x<-3\)?

III tells us that \(x>3\) or \(x<-1\). So is \(x>3\) or \(x<-3\)? YES

\(x>3\) from question => \(x>3\)from III: Correct \(x<-3\) from question => \(x<-1\) from III: Correct as well. We are asked if x<-3 and III tells us that x<-1 so for sure it will be <-3 also.

A. I only B. II only C. I and II only D. II and III only E. I, II, and III

What if x = -2 that is < -1 but > than -3 so IIImust be out?no

Zarrolou wrote:

Archit143 wrote:

I too have the same doubt...can anyone address the query

Archit

The question asks is \(x>3\) or \(x<-3\)?

III tells us that \(x>3\) or \(x<-1\). So is \(x>3\) or \(x<-3\)? YES

\(x>3\) from question => \(x>3\)from III: Correct \(x<-3\) from question => \(x<-1\) from III: Correct as well. We are asked if x<-3 and III tells us that x<-1 so for sure it will be <-3 also.

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

28 Oct 2014, 09:53

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

23 Nov 2014, 22:46

Hi All,

After going through the explanations I could understand why option B was not correct. But I am sure under timed conditions, I might make a similar mistake. Does anyone have a way to solve such problems, so that a mistake can be avoided and an important case like the 3rd option be considered while evaluating answer choices?

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

23 Nov 2014, 23:29

aj0809 wrote:

Hi All,

After going through the explanations I could understand why option B was not correct. But I am sure under timed conditions, I might make a similar mistake. Does anyone have a way to solve such problems, so that a mistake can be avoided and an important case like the 3rd option be considered while evaluating answer choices?

Thanks, AK

Hi AK,

Why will you leave an option out...that's a big no...in this question St 2 is true so you can remove answer options which don't have st 2 as one of the option and see if it reduces your work load... You may want to refresh some basics on how to go about solving such questions..

This is why we need to practice and see where we are going wrong...For instance this is an important pointer for you to never to overlook an option..

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

23 Nov 2014, 23:43

Thanks WondedTiger,

Maybe I didn't present my question correctly. I didn't leave the 3rd option but came to the conclusion that it was wrong and chose my answer as B. I just want to prevent that in timed conditions for difficult questions like these, which have subtle differences that makes an answer choice right.

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

23 Nov 2014, 23:53

aj0809 wrote:

Thanks WondedTiger,

Maybe I didn't present my question correctly. I didn't leave the 3rd option but came to the conclusion that it was wrong and chose my answer as B. I just want to prevent that in timed conditions for difficult questions like these, which have subtle differences that makes an answer choice right.

hmm..

Did you solve the 3rd option correctly or you made it a mistake. Identify the step where you made the mistake.. Consider making an error log..That will certainly help...
_________________

“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”

Maybe I didn't present my question correctly. I didn't leave the 3rd option but came to the conclusion that it was wrong and chose my answer as B. I just want to prevent that in timed conditions for difficult questions like these, which have subtle differences that makes an answer choice right.

Try using the number line for inequalities and absolute values.

|x| > 3 means distance of x from 0 is more than 3. So x is either greater than 3 or less than -3. So on the number line, it looks like this:

___________-3________0________3____________

The red part is the range where x will lie.

Is |x-1| > 2? |x-1| > 2 represents that distance of x from 1 is more than 2. So x is either greater than 3 or less than -1. Is x either greater than 3 or less than -1?

___________-3________0________3____________

All points on the red lines satisfy this. They are either greater than 3 or less than -1.

If |x|>3, which of the following must be true? [#permalink]

Show Tags

22 May 2015, 06:26

III. |x-1|>2 This implies that the distance of x from 1 must be greater than 2. So x is either greater than 3 or less than -1. Now, recall all the values that x can take. For each value, can be say that x is either greater than 3 or less than -1? Yes. 3.00001 - x is greater than 3 3.5 : x is greater than 3 4.2 : x is greater than 3 5.7 : x is greater than 3 67 : x is greater than 3 1000 : x is greater than 3 -3.45 : x is less than -1 -4 : x is less than -1 -8 : x is less than -1 -100 : x is less than -1

For every value that x can take, x will be either greater than 3 or less than -1. Note that we are not saying that every value less than -1 must be valid for x. We are saying that every value that is valid for x (found by using |x| > 3) will be either greater than 3 or less than -1.Hence |x-1|>2 must be true for every value that x can take.

VeritasPrepKarishma Thank you for this! I was doing 'must be true' questions wrong!

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

11 Sep 2016, 08:33

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Re: If |x|>3, which of the following must be true? [#permalink]

Show Tags

13 Nov 2016, 20:24

Zarrolou wrote:

Archit143 wrote:

I too have the same doubt...can anyone address the query

Archit

The question asks is \(x>3\) or \(x<-3\)?

III tells us that \(x>3\) or \(x<-1\). So is \(x>3\) or \(x<-3\)? YES

\(x>3\) from question => \(x>3\)from III: Correct \(x<-3\) from question => \(x<-1\) from III: Correct as well. We are asked if x<-3 and III tells us that x<-1 so for sure it will be <-3 also.

A. I only B. II only C. I and II only D. II and III only E. I, II, and III

I can't understand how the official answer can be right. For me is B. Please respond and I'll provide official explanation! Thanks

Responding to a pm:

|x| > 3 implies that x is a point whose distance from 0 is more than 3. So x could be greater than 3 or less than -3. Before you move further, think about the values x can take: 3.00001, 3.5, 4.2, 5.7, 67, 1000, -3.45, -4, -8, -100 etc. The only values it cannot take are -3 <= x <= 3

Which of the following must be true?

I. x > 3

For every value that x can take, must x be greater than 3? No. e.g. if x takes -3.45, -4 etc, it will not be greater than 3 so this is not true.

II. X^2 > 9 This is the same as |x| > 3 so it must be true

III. |x-1|>2 This implies that the distance of x from 1 must be greater than 2. So x is either greater than 3 or less than -1. Now, recall all the values that x can take. For each value, can be say that x is either greater than 3 or less than -1? Yes. 3.00001 - x is greater than 3 3.5 : x is greater than 3 4.2 : x is greater than 3 5.7 : x is greater than 3 67 : x is greater than 3 1000 : x is greater than 3 -3.45 : x is less than -1 -4 : x is less than -1 -8 : x is less than -1 -100 : x is less than -1

For every value that x can take, x will be either greater than 3 or less than -1. Note that we are not saying that every value less than -1 must be valid for x. We are saying that every value that is valid for x (found by using |x| > 3) will be either greater than 3 or less than -1. Hence |x-1|>2 must be true for every value that x can take.

Responding to a pm:

Quote:

I couldn't understand the solution for option B.

Since |x|>3 we can say that |x|-1>2 ( subtracting 2 from both sides).

But how are we saying that |x|-1 is equal to |x-1|.

They are not the same: |x - 1| > 2 and |x|-1 > 2

|x - 1| > 2 means x > 3 or x < -1

|x| - 1 > 2 |x| > 3 means x > 3 or x < -3

But not what is given and what is asked. We are GIVEN that |x| > 3 So we KNOW that x is either greater than 3 or it is less than -3. So valid values for x are 3.4, 4, 101, 2398675, -3.6, -5, -78 etc

Now the question is: "Is |x - 1| > 2?" "Is x always either greater than 3 or less than -1?" All positive values of x are given to be greater than 3. All negative values of x are given to be less than -3. So obviously they are less than -1 too.

Happy New Year everyone! Before I get started on this post, and well, restarted on this blog in general, I wanted to mention something. For the past several months...

It’s quickly approaching two years since I last wrote anything on this blog. A lot has happened since then. When I last posted, I had just gotten back from...

Happy 2017! Here is another update, 7 months later. With this pace I might add only one more post before the end of the GSB! However, I promised that...

The words of John O’Donohue ring in my head every time I reflect on the transformative, euphoric, life-changing, demanding, emotional, and great year that 2016 was! The fourth to...