Last visit was: 19 Nov 2025, 20:01 It is currently 19 Nov 2025, 20:01
Close
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.

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.
Close
Request Expert Reply
Confirm Cancel
avatar
saxenagarima
Joined: 07 Sep 2010
Last visit: 10 Jun 2011
Posts: 4
Own Kudos:
96
 [96]
Given Kudos: 4
Posts: 4
Kudos: 96
 [96]
6
Kudos
Add Kudos
90
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,381
 [21]
11
Kudos
Add Kudos
10
Bookmarks
Bookmark this Post
General Discussion
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
778,381
 [4]
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,381
 [4]
3
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
avatar
saxenagarima
Joined: 07 Sep 2010
Last visit: 10 Jun 2011
Posts: 4
Own Kudos:
Given Kudos: 4
Posts: 4
Kudos: 96
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
saxenagarima
If 4x-12 >= x + 9, which of the following must be true

a) X > 6
b) X < 7
C) X > 7
D) X > 8
E) X < 8

I doubt the OA in MGMAT solutions

Given: \(4x-12\geq{x + 9}\) --> \(3x\geq{21}\) --> \(x\geq{7}\).

Only A is always true, as ANY \(x\) from the TRUE range \(x\geq{7}\) will be more than 6.

Answer: A.


But with A) x can be 6.1, which will not satisfy the given equation.....
shouldn't option C) be valid choice ....
User avatar
Joy111
Joined: 18 Oct 2010
Last visit: 25 Dec 2013
Posts: 56
Own Kudos:
Given Kudos: 26
Posts: 56
Kudos: 604
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel

If \(-1<x<0\) or \(x>1\), then which of the following must be true about \(x\):
A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|^2>1

As \(-1<x<0\) or \(x>1\) then ANY \(x\) from these ranges would satisfy \(x>-1\). So B is always true.

\(x\) could be for example -1/2, -3/4, or 10 but no matter what \(x\) actually is it's IN ANY CASE more than -1. So we can say about \(x\) that it's more than -1.

On the other hand for example A is not always true as it says that \(x>1\), which is not always true as \(x\) could be -1/2 and -1/2 is not more than 1.

Hope it's clear.

just for the sake of learning please tell me how to evaluate option E. |X|^2>1

is it |x|>1 and |x|>-1

if |x|>1 then -1 >x>1

if |x|>-1 then how do we evaluate this part, confused here.
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,381
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Joy111
Bunuel

If \(-1<x<0\) or \(x>1\), then which of the following must be true about \(x\):
A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|^2>1

As \(-1<x<0\) or \(x>1\) then ANY \(x\) from these ranges would satisfy \(x>-1\). So B is always true.

\(x\) could be for example -1/2, -3/4, or 10 but no matter what \(x\) actually is it's IN ANY CASE more than -1. So we can say about \(x\) that it's more than -1.

On the other hand for example A is not always true as it says that \(x>1\), which is not always true as \(x\) could be -1/2 and -1/2 is not more than 1.

Hope it's clear.

just for the sake of learning please tell me how to evaluate option E. |X|^2>1

is it |x|>1 and |x|>-1

if |x|>1 then -1 >x>1

if |x|>-1 then how do we evaluate this part, confused here.

|x|^2>1 is the same as x^2>1, so it holds true for x<-1 and x>1.

As for |x|>-1: it holds true for ANY value of x, because absolute value of a number is always non-negative.

Hope it helps.
User avatar
Joy111
Joined: 18 Oct 2010
Last visit: 25 Dec 2013
Posts: 56
Own Kudos:
Given Kudos: 26
Posts: 56
Kudos: 604
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Joy111
Bunuel

If \(-1<x<0\) or \(x>1\), then which of the following must be true about \(x\):
A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|^2>1

As \(-1<x<0\) or \(x>1\) then ANY \(x\) from these ranges would satisfy \(x>-1\). So B is always true.

\(x\) could be for example -1/2, -3/4, or 10 but no matter what \(x\) actually is it's IN ANY CASE more than -1. So we can say about \(x\) that it's more than -1.

On the other hand for example A is not always true as it says that \(x>1\), which is not always true as \(x\) could be -1/2 and -1/2 is not more than 1.

Hope it's clear.

just for the sake of learning please tell me how to evaluate option E. |X|^2>1

is it |x|>1 and |x|>-1

if |x|>1 then -1 >x>1

if |x|>-1 then how do we evaluate this part, confused here.

|x|^2>1 is the same as x^2>1, so it holds true for x<-1 and x>1.

As for |x|>-1: it holds true for ANY value of x, because absolute value of a number is always non-negative.

Hope it helps.

ok , thank you for that .

Now suppose |x|>-1 was one of the options of the question , then couldn't this have been one of the solutions .

can you please show how |x|>-1 fails to satisfy all the values of x in the equation

If -1< x <0 or x >1 then which of the following must be true about x :
A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|>-1

now for all values of x i.e x=-1/2, x=3 ,x=4, option E also is also satisfied .

seems to me that both A and E ,could be the solutions? please correct me . Thank you.
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
778,381
 [2]
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,381
 [2]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Joy111

ok , thank you for that .

Now suppose |x|>-1 was one of the options of the question , then couldn't this have been one of the solutions .

can you please show how |x|>-1 fails to satisfy all the values of x in the equation

If -1< x <0 or x >1 then which of the following must be true about x :
A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|>-1

now for all values of x i.e x=-1/2, x=3 ,x=4, option E also is also satisfied .

seems to me that both A and E ,could be the solutions? please correct me . Thank you.

The question in my example is as follows:

If \(-1<x<0\) or \(x>1\), then which of the following must be true about \(x\):

A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|^2>1

For this question E cannot be correct since if x=-1/2 then |x|^2>1 does not hold true.

Hope it's clear.
avatar
dcastan2
Joined: 28 Apr 2012
Last visit: 25 Feb 2013
Posts: 13
Own Kudos:
Given Kudos: 51
Posts: 13
Kudos: 74
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
saxenagarima
If 4x-12 >= x + 9, which of the following must be true

a) X > 6
b) X < 7
C) X>7
D) X>8
E) X < 8

I doubt the OA in MGMAT solutions

Given: \(4x-12\geq{x + 9}\) --> \(3x\geq{21}\) --> \(x\geq{7}\).

Only A is always true, as ANY \(x\) from the TRUE range \(x\geq{7}\) will be more than 6.

Answer: A.

Bunuel,
I must be reading the question incorrectly because I feel that after you get x>=7 you think 7=7 and 8>7 so the answer of x could 7 or 8 but since it is asking which is always greater than the answer would be D. 8. I don't see why we would look at it as x>6 when we solved the equation and got x>=7. How would the question need to be worded for that to be the case because I am really confused. I don't feel that in other OG questions we we replaced the x with a number smaller when it is asking what number is greater than or equal to a number larger. If that's the case, that means C, D, and E were the trap answers? I'd appreciate your help. Thanks!

If , then which of the following must be true about :
A. x=3
B. x^2=10
C. x<4
D. |x|=1
E. x>-10

Answer is E (x>-10), because as x=5 then it's more than -10.

And for this one I know it can't be A-D, but for E, x could be -9 which wouldn't necessarily mean that it is greater than 5? Would you choose it anyways?
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
778,381
 [1]
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,381
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
dcastan2
Bunuel
saxenagarima
If 4x-12 >= x + 9, which of the following must be true

a) X > 6
b) X < 7
C) X>7
D) X>8
E) X < 8

I doubt the OA in MGMAT solutions

Given: \(4x-12\geq{x + 9}\) --> \(3x\geq{21}\) --> \(x\geq{7}\).

Only A is always true, as ANY \(x\) from the TRUE range \(x\geq{7}\) will be more than 6.

Answer: A.

Bunuel,
I must be reading the question incorrectly because I feel that after you get x>=7 you think 7=7 and 8>7 so the answer of x could 7 or 8 but since it is asking which is always greater than the answer would be D. 8. I don't see why we would look at it as x>6 when we solved the equation and got x>=7. How would the question need to be worded for that to be the case because I am really confused. I don't feel that in other OG questions we we replaced the x with a number smaller when it is asking what number is greater than or equal to a number larger. If that's the case, that means C, D, and E were the trap answers? I'd appreciate your help. Thanks!

If , then which of the following must be true about :
A. x=3
B. x^2=10
C. x<4
D. |x|=1
E. x>-10

Answer is E (x>-10), because as x=5 then it's more than -10.

And for this one I know it can't be A-D, but for E, x could be -9 which wouldn't necessarily mean that it is greater than 5? Would you choose it anyways?

I think you are confused about what is given and what is asked.

Given that \(x\geq{7}\), so \(x\) is some number which is more than or equal to 7. Now, the question asks, what must be true about \(x\) (which we know is more than or equal to 7).

If \(x\) is more than or equal to 7, then it must be true that \(x\) is greater than 6, thus A must be true.

The same with another example in your post: given that \(x=5\). The question asks, what must be true about \(x\). Since, \(x=5\), thus it's true to say that it's greater than -10.

Hope it's clear.
avatar
Moralhazard
Joined: 28 Jan 2012
Last visit: 01 Jul 2013
Posts: 2
Own Kudos:
14
 [2]
Given Kudos: 3
Location: Viet Nam
Concentration: Entrepreneurship, Nonprofit
GMAT 1: 650 Q47 V33
GPA: 3.7
WE:Investment Banking (Non-Profit and Government)
GMAT 1: 650 Q47 V33
Posts: 2
Kudos: 14
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi Bunuel,
I am not quite satisfied with the OA. Since the question is not clear if x is an integer, for example x = 6.5 <7 => then it is not true. So the correct choice answer should be C

What do you think?
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 19 Nov 2025
Posts: 105,390
Own Kudos:
Given Kudos: 99,977
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 105,390
Kudos: 778,381
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Moralhazard
Hi Bunuel,
I am not quite satisfied with the OA. Since the question is not clear if x is an integer, for example x = 6.5 <7 => then it is not true. So the correct choice answer should be C

What do you think?

We are not told that x is an integer but it has nothing to do with the question.

x cannot be 6.5 because we are told that \(x\geq{7}\).

Option C (x>7) is not always true, since x can be 7 and in this case x>7 won't hold true.

Hope it's clear.
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 19 Nov 2025
Posts: 6,839
Own Kudos:
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
Expert
Expert reply
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 6,839
Kudos: 16,354
Kudos
Add Kudos
Bookmarks
Bookmark this Post
arhumsid
If \(4x - 12 > x + 9\), which o f the following must be true?

A. \(x > 6\)
B. \(x < 7\)
C. \(x > 7\)
D. \(x > 8\)
E. \(x < 8\)

Im confused with the 'must be true' part. Once you choose an answer, please explain why others cant be correct.

Solving \(4x - 12 > x + 9\)
i.e. \(4x - x > 12 + 9\)
i.e. \(3x > 21\)
i.e. \(x > 7\)

Answer: option C

A. \(x > 6\) is Incorrect because as per this option x may be 6.5 whereas x must be Essentially Greater than 7
B. \(x < 7\) is Completely Incorrect because x must be Essentially Greater than 7
C. \(x > 7\) is CORRECT (Exactly what we have derived)
D. \(x > 8\) is Incorrect because as per this option x can NOT be 7.5 whereas x must be Essentially Greater than 7 which can be 7.5 as well
E. \(x < 8\) is Incorrect because as per this option x can NOT be 8.5 whereas x must be Essentially Greater than 7 and can be anything greater than 8 as well

I hope this helps and clears your doubt!
User avatar
rishit1080
Joined: 19 Oct 2016
Last visit: 07 Apr 2017
Posts: 55
Own Kudos:
Given Kudos: 29
Location: India
Concentration: Marketing, Leadership
Schools: IIMA  (I)
GMAT 1: 580 Q46 V24
GMAT 2: 540 Q39 V25
GMAT 3: 660 Q48 V34
GPA: 3.15
WE:Psychology and Counseling (Healthcare/Pharmaceuticals)
Schools: IIMA  (I)
GMAT 3: 660 Q48 V34
Posts: 55
Kudos: 81
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
saxenagarima
If 4x-12 >= x + 9, which of the following must be true

a) X > 6
b) X < 7
C) X>7
D) X>8
E) X < 8

I doubt the OA in MGMAT solutions

Given: \(4x-12\geq{x + 9}\) --> \(3x\geq{21}\) --> \(x\geq{7}\).

Only A is always true, as ANY \(x\) from the TRUE range \(x\geq{7}\) will be more than 6.

Answer: A.

Similar question to practice: https://gmatclub.com/forum/if-it-is-true ... 29093.html


Just wanted to let you know your post made me realize and go OHHHHHHHHHHHH! I get it now. Thanks B
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,977
Own Kudos:
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,977
Kudos: 8,394
Kudos
Add Kudos
Bookmarks
Bookmark this Post
saxenagarima
If 4x-12 >= x + 9, which of the following must be true

A. x > 6
B. x < 7
C. x > 7
D. x > 8
E. x < 8

Let’s solve the given inequality:

4x - 12 ≥ x + 9

3x ≥ 21

x ≥ 7

Thus, x must be greater than 6.

Answer: A
User avatar
Fdambro294
Joined: 10 Jul 2019
Last visit: 20 Aug 2025
Posts: 1,350
Own Kudos:
Given Kudos: 1,656
Posts: 1,350
Kudos: 742
Kudos
Add Kudos
Bookmarks
Bookmark this Post
4x - 12 >/= x + 9

after algebraic manipulation, you end up with:

x >/= 7


Q asks: Which of the following must be True?

the Question is effectively asking: which statement in the Answer Choices is a TRUE Statement for Every Possible Value that X can Take?

X can take every value from 7 - to - infinite

-C- X > 7

Since X can take the value of 7, the Statement X > 7 can be FALSE


-A- X > 6

for every value that X can take based on our GIVEN Constraint X >/= 7, we can say "yes, this X Value is greater than > 6"

-A- must be True
User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,070
Own Kudos:
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,070
Kudos: 19,393
Kudos
Add Kudos
Bookmarks
Bookmark this Post
4x - 12 ≥ x + 9

=> 4x - x ≥ 9 + 12

=> 3x ≥ 21

=> x ≥ 7

Option A: x > 6 satisfies it.

Answer A
User avatar
Mugdho
Joined: 27 Feb 2019
Last visit: 11 Nov 2023
Posts: 93
Own Kudos:
Given Kudos: 495
Posts: 93
Kudos: 239
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Or:
If \(-1<x<0\) or \(x>1\), then which of the following must be true about \(x\):
A. x>1
B. x>-1
C. |x|<1
D. |x|=1
E. |x|^2>1

As \(-1<x<0\) or \(x>1\) then ANY \(x\) from these ranges would satisfy \(x>-1\). So B is always true.

\(x\) could be for example -1/2, -3/4, or 10 but no matter what \(x\) actually is it's IN ANY CASE more than -1. So we can say about \(x\) that it's more than -1.

On the other hand for example A is not always true as it says that \(x>1\), which is not always true as \(x\) could be -1/2 and -1/2 is not more than 1.

Hope it's clear.[/quote]


Hey Bunuel if we take x>-1 in 3rd example, like x=10, then this doesn’t satisfy x<0.. So what's the logic here ?

Posted from my mobile device
avatar
Trest
Joined: 22 Jul 2019
Last visit: 18 Nov 2022
Posts: 5
Own Kudos:
23
 [1]
Given Kudos: 29
Posts: 5
Kudos: 23
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
What I found helped for must-be true questions is to find the statement that is OUTSIDE the range and is also true.

Given x >= 7, we can eliminate all the choices from B to E since points 7 and 8 they fall within that range.

A is the only option outside the range x >= 7 and the statement is also true.

These links helped: https://gmatclub.com/forum/veritas-prep ... l#p1858991
https://gmatclub.com/forum/veritas-prep ... l#p1772059
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,589
Own Kudos:
Posts: 38,589
Kudos: 1,079
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderators:
Math Expert
105390 posts
Tuck School Moderator
805 posts