Last visit was: 11 Jul 2025, 16:57 It is currently 11 Jul 2025, 16:57
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
User avatar
gmatbull
Joined: 21 Dec 2009
Last visit: 04 Feb 2018
Posts: 335
Own Kudos:
2,624
 [22]
Given Kudos: 20
Concentration: Entrepreneurship, Finance
Posts: 335
Kudos: 2,624
 [22]
2
Kudos
Add Kudos
20
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
gurpreetsingh
Joined: 12 Oct 2009
Last visit: 15 Jun 2019
Posts: 2,273
Own Kudos:
3,857
 [6]
Given Kudos: 235
Status:<strong>Nothing comes easy: neither do I want.</strong>
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Products:
Schools: ISB '15 (M)
GMAT 2: 710 Q50 V35
Posts: 2,273
Kudos: 3,857
 [6]
4
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
General Discussion
User avatar
shaselai
User avatar
Current Student
Joined: 12 Jun 2009
Last visit: 17 Jun 2019
Posts: 1,675
Own Kudos:
433
 [3]
Given Kudos: 52
Status:What's your raashee?
Location: United States (NC)
Concentration: Strategy, Finance
Schools: UNC (Kenan-Flagler) - Class of 2013
GMAT 1: 720 Q49 V39
WE:Programming (Computer Software)
Products:
Schools: UNC (Kenan-Flagler) - Class of 2013
GMAT 1: 720 Q49 V39
Posts: 1,675
Kudos: 433
 [3]
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
gurpreetsingh
Joined: 12 Oct 2009
Last visit: 15 Jun 2019
Posts: 2,273
Own Kudos:
Given Kudos: 235
Status:<strong>Nothing comes easy: neither do I want.</strong>
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Products:
Schools: ISB '15 (M)
GMAT 2: 710 Q50 V35
Posts: 2,273
Kudos: 3,857
Kudos
Add Kudos
Bookmarks
Bookmark this Post
shaselai : Nice one 8-)
User avatar
shrouded1
User avatar
Retired Moderator
Joined: 02 Sep 2010
Last visit: 29 Apr 2018
Posts: 609
Own Kudos:
3,127
 [2]
Given Kudos: 25
Location: London
 Q51  V41
Products:
Posts: 609
Kudos: 3,127
 [2]
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
gmatbull
please how do i go about this question?
I considered various options, but none seems attractive to me:

|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)

\(|x+1| < |x^2+2x+1+1|\)
\(|x+1| < |(x+1)^2 + 1|\)

Note that \((x+1)^2+1\) is always positive, so,

\(|x+1| < x^2+2x+2\)

If x+1>=0 OR x>=-1, Then
\(x^2+x+1>0\)
b^2-4ac = -3 ... No real roots and a>0 .. So this function is always positive
But assumption is x>-1
So x>=-1

If x+1<0 OR x<-1, Then
\(x^2+3x+3>0\)
b^2-4ac = -3 ... No real roots and a>0 .. So this function is always positive
But assumption is x<-1
So x<-1

Combining, all values of x satisfy this relation

Answer is (a)
User avatar
shrouded1
User avatar
Retired Moderator
Joined: 02 Sep 2010
Last visit: 29 Apr 2018
Posts: 609
Own Kudos:
Given Kudos: 25
Location: London
 Q51  V41
Products:
Posts: 609
Kudos: 3,127
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Ok, reading the solutions above ... I officially believe I just used a sledge hammer to kill an ant
User avatar
gurpreetsingh
Joined: 12 Oct 2009
Last visit: 15 Jun 2019
Posts: 2,273
Own Kudos:
Given Kudos: 235
Status:<strong>Nothing comes easy: neither do I want.</strong>
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Products:
Schools: ISB '15 (M)
GMAT 2: 710 Q50 V35
Posts: 2,273
Kudos: 3,857
Kudos
Add Kudos
Bookmarks
Bookmark this Post
shrouded1
Ok, reading the solutions above ... I officially believe I just used a sledge hammer to kill an ant

lets see the size of the hammer 8-)
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 11 Jul 2025
Posts: 102,635
Own Kudos:
740,495
 [3]
Given Kudos: 98,172
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,635
Kudos: 740,495
 [3]
1
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
gurpreetsingh
gmatbull
please how do i go about this question?
I considered various options, but none seems attractive to me:

|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)

\(|x + 1| < |x^2 + 2x + 2|\) since \(x^2 + 2x + 2 = (x+1)^2 +1\) which is always > 0

=> \(|x + 1| < (x+1)^2 +1\) take \(|x+1| = y\)

=> \(y<y^2 +1\) => \(y^2 +1 - y>0\)

\((y-\frac{1}{2})^2 +\frac{3}{4}>0\)

This is true for all values of y, hence it is true for all values of x.

Hence A

Good approach.

Though you could stop already at the stage \(|x + 1|<|(x+1)^2 +1|\). As it's clear that this inequality holds true for all x-es: if \(|x + 1|\geq{1}\) then clearly \(|x + 1|<(x+1)^2\) and if \(|x + 1|<{1}\) then \(LHS<1\) BUT \(RHS=|(x+1)^2 +1|>1\).
User avatar
mainhoon
Joined: 18 Jul 2010
Last visit: 10 Oct 2013
Posts: 534
Own Kudos:
Given Kudos: 15
Status:Apply - Last Chance
Affiliations: IIT, Purdue, PhD, TauBetaPi
Concentration: $ Finance $
Schools:Wharton, Sloan, Chicago, Haas
 Q50  V37
GPA: 4.0
WE 1: 8 years in Oil&amp;Gas
Posts: 534
Kudos: 381
Kudos
Add Kudos
Bookmarks
Bookmark this Post
shrouded1
gmatbull
please how do i go about this question?
I considered various options, but none seems attractive to me:

|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)

\(|x+1| < |x^2+2x+1+1|\)
\(|x+1| < |(x+1)^2 + 1|\)

Note that \((x+1)^2+1\) is always positive, so,

\(|x+1| < x^2+2x+2\)

If x+1>=0 OR x>=-1, Then
\(x^2+x+1>0\)
b^2-4ac = -3 ... No real roots and a>0 .. So this function is always positive
But assumption is x>-1
So x>=-1

If x+1<0 OR x<-1, Then
\(x^2+3x+3>0\)
b^2-4ac = -3 ... No real roots and a>0 .. So this function is always positive
But assumption is x<-1
So x<-1

Combining, all values of x satisfy this relation

Answer is (a)

Explain the no real roots and a>0, hence always positive part...
User avatar
shrouded1
User avatar
Retired Moderator
Joined: 02 Sep 2010
Last visit: 29 Apr 2018
Posts: 609
Own Kudos:
3,127
 [1]
Given Kudos: 25
Location: London
 Q51  V41
Products:
Posts: 609
Kudos: 3,127
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
probably beyond the scope of the GMAT but here goes :

No real roots (discriminant < 0) implies the parabola does not intersect the X-axis

And coeff of x^2 (or 'a') > 0 implies it is upward facing

If you plot it out, you will see this is only possible if the parabola only exists in the upper two quadrants ==> it can never take a negative value
User avatar
mainhoon
Joined: 18 Jul 2010
Last visit: 10 Oct 2013
Posts: 534
Own Kudos:
Given Kudos: 15
Status:Apply - Last Chance
Affiliations: IIT, Purdue, PhD, TauBetaPi
Concentration: $ Finance $
Schools:Wharton, Sloan, Chicago, Haas
 Q50  V37
GPA: 4.0
WE 1: 8 years in Oil&amp;Gas
Posts: 534
Kudos: 381
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Reminds me of the JEE days.. Well those things can come in handy...

Posted from my mobile device
User avatar
mainhoon
Joined: 18 Jul 2010
Last visit: 10 Oct 2013
Posts: 534
Own Kudos:
Given Kudos: 15
Status:Apply - Last Chance
Affiliations: IIT, Purdue, PhD, TauBetaPi
Concentration: $ Finance $
Schools:Wharton, Sloan, Chicago, Haas
 Q50  V37
GPA: 4.0
WE 1: 8 years in Oil&amp;Gas
Posts: 534
Kudos: 381
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Interestingly if visualized graphically, y=|x+1| is a V shaped plot, with y= 0 at x= -1 place where it turns around...

Y=|(x+1)^2+1| is a parabola and is clearly above the previous V shape. Check lowest it would fall is 1 at x= -1...

Posted from my mobile device
User avatar
gmatbull
Joined: 21 Dec 2009
Last visit: 04 Feb 2018
Posts: 335
Own Kudos:
Given Kudos: 20
Concentration: Entrepreneurship, Finance
Posts: 335
Kudos: 2,624
Kudos
Add Kudos
Bookmarks
Bookmark this Post
All your contributions were really helpful.
Thanks to your guys, especially "gurpreetsingh" and "shaselai."
User avatar
jpr200012
Joined: 30 May 2010
Last visit: 10 Oct 2011
Posts: 137
Own Kudos:
Given Kudos: 32
Posts: 137
Kudos: 822
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Was A the OA? Also, what is the source?
User avatar
gmatbull
Joined: 21 Dec 2009
Last visit: 04 Feb 2018
Posts: 335
Own Kudos:
Given Kudos: 20
Concentration: Entrepreneurship, Finance
Posts: 335
Kudos: 2,624
Kudos
Add Kudos
Bookmarks
Bookmark this Post
got the question from a set of question on the internet, but no OA was
provided; however, I feel the explanations are very clear enough.
User avatar
jpr200012
Joined: 30 May 2010
Last visit: 10 Oct 2011
Posts: 137
Own Kudos:
Given Kudos: 32
Posts: 137
Kudos: 822
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Thanks. I was just curious of the source. I'm always looking for tough problems :)
User avatar
sujoykrdatta
Joined: 26 Jun 2014
Last visit: 10 Jul 2025
Posts: 539
Own Kudos:
Given Kudos: 13
Status:Mentor & Coach | GMAT Q51 | CAT 99.98
Expert
Expert reply
Posts: 539
Kudos: 1,039
Kudos
Add Kudos
Bookmarks
Bookmark this Post
gmatbull
|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)


If you are comfortable with graphs - sketching rough graphs based on the expression, it is very easy to get the solution to the above:

Attachment:
1.JPG
1.JPG [ 126.93 KiB | Viewed 4442 times ]

Since the graph of |x2 + 2x + 2| is always above the graph of |x+1|, we have: |x + 1| < |x^2 + 2x + 2| for all x

Answer A


Alternative approach:

|x + 1| < |x^2 + 2x + 2|

=> |x+1| < |(x+1)^2 + 1|

Let |x+1| = p => (x+1)^2 = |(x+1)|^2 = p^2
Note that p is always positive since p = |x+1|; thus p can be either 0<p<1 or p>1

=> We have: p < |p^2 + 1|

# The RHS is always greater than 1, hence is always true for all fractional 0 < p < 1
# For p > 1: p^2 > p => p^2 + 1 > p > 0

Thus, the above is true for all p

Answer A
User avatar
HoudaSR
Joined: 08 Aug 2022
Last visit: 24 Nov 2023
Posts: 72
Own Kudos:
Given Kudos: 182
Location: Morocco
WE:Advertising (Non-Profit and Government)
Kudos
Add Kudos
Bookmarks
Bookmark this Post
gmatbull
|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)


Bunuel KarishmaB I need your help with this one please.

When I try to solve this algebraically, I get the following two inequalities, for which there are no solutions: x^2+x+1>0 and x^2+3x+3>0.

My first reflex was to answer this question as D: No solutions, but then when I went and I plugged in numbers I realised that whichever numbers I was picking they were making the inequality true.

I am a bit confused about how to approach these type of absolute value questions that involve quadratics that turn out to have no solutions.

Thank you in advance.
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 10 Jul 2025
Posts: 16,101
Own Kudos:
74,262
 [2]
Given Kudos: 475
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,101
Kudos: 74,262
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
HoudaSR
gmatbull
|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)


Bunuel KarishmaB I need your help with this one please.

When I try to solve this algebraically, I get the following two inequalities, for which there are no solutions: x^2+x+1>0 and x^2+3x+3>0.

My first reflex was to answer this question as D: No solutions, but then when I went and I plugged in numbers I realised that whichever numbers I was picking they were making the inequality true.

I am a bit confused about how to approach these type of absolute value questions that involve quadratics that turn out to have no solutions.

Thank you in advance.

How did you get these inequalities: x^2+x+1>0 and x^2+3x+3>0 ? By removing the absolute value signs? Ok.

But I am not sure what you mean by "no solutions."
They don't have any roots (the discriminant is negative) because their parabolas lie above the X axis. So if you put x^2+x+1 = 0 you won't get any values of x. The value of x^2+x+1 is always positive, for all values of x and that is why all values of x satisfy x^2+x+1>0.
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 10 Jul 2025
Posts: 16,101
Own Kudos:
74,262
 [1]
Given Kudos: 475
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,101
Kudos: 74,262
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
gmatbull
|x + 1| < |x^2 + 2x + 2|

A: (-infinity, +infinity)
B: (-1, +infinity)
C: (-infinity, -1)
D: no solutions
E: (-1, 1)

If you are looking for the exact set of values that satisfy this condition, best method here would be to try some values.
Put x = 0. It satisfies. It means the answer is not (C), (D) or (E).

Put x = -2. It satisfies. It means answer is not (B).

By elimination, answer (A)
 1   2   
Moderators:
Math Expert
102635 posts
PS Forum Moderator
688 posts