GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 21 Mar 2019, 08:54

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

If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 7101
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 21 Aug 2016, 00:04
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

76% (01:51) correct 24% (02:16) wrong based on 147 sessions

HideShow timer Statistics

If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?
A. √2
B. ±√2
C. 1
D. 2
E. √5

*An answer will be posted in 2 days.

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7424
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 21 Aug 2016, 00:46
MathRevolution wrote:
If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?
A. √2
B. ±√2
C. 1
D. 2
E. √5

*An answer will be posted in 2 days.


Hi,

two ways to do it..

1) substitute value
when you substitute value of x as √2 , we get the required answer, BUT the value √2 is also in B..
check for -√2 , you will get answer as B..

2) proper method
\(\frac{1}{x(x+1)}+\frac{1}{(x+1)(x+2)}=\frac{1}{(x+1)}\)....
\(\frac{1}{(x+1)}(\frac{1}{x}+\frac{1}{(x+2)}-1)=0\)....
so either \frac{1}{(x+1)}=0, that is not posible as numerator cannot be 0..
so \((\frac{1}{x}+\frac{1}{(x+2)}-1)=0......\frac{x+2+x-x^2-2x}{x(x+2)}=0\)....
\(x+2+x-x^2-2x=0........x^2=2....\)or x= ±√2
B
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html


GMAT Expert

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 7101
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 22 Aug 2016, 19:50
If we solve the question, we get x=±√2.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Senior Manager
Senior Manager
avatar
Joined: 23 Apr 2015
Posts: 302
Location: United States
Concentration: General Management, International Business
WE: Engineering (Consulting)
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 23 Aug 2016, 09:14
MathRevolution wrote:
If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?
A. √2
B. ±√2
C. 1
D. 2
E. √5

*An answer will be posted in 2 days.



This is a straight algebraic equation with no catch. How come listed as 600-700 category question ?
Manager
Manager
User avatar
B
Joined: 19 Jul 2017
Posts: 85
Location: India
Concentration: General Management, Strategy
GPA: 3.5
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 17 Sep 2017, 08:24
MathRevolution wrote:
If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?
A. √2
B. ±√2
C. 1
D. 2
E. √5

*An answer will be posted in 2 days.



From the Question stem cancel out the common denominator x+1;

so it becomes (1/x)+(1/x+2)=1;

Solving this we get x+2+x = x(x+2);

2x+2=x^+2x
so x= ±√2
Ans:B
VP
VP
avatar
G
Joined: 09 Mar 2018
Posts: 1007
Location: India
If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 18 Oct 2018, 23:12
Given : 1/x(x+1) + 1/((x+1)(x+2))=1/(x+1)

Take the LCM in LHS, making the LHS as

\(\frac{2x+2}{x*(x+1)* (x+2)}\) = \(\frac{1}{x+1}\)

Now if you cross multiply the denominator of LHS to RHS

Equation will be reduced to

2x + 2 = x^2 + 2x

\(x^2\) = 2

Giving answer as B
_________________

If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

Intern
Intern
avatar
B
Joined: 04 Apr 2018
Posts: 21
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 20 Oct 2018, 11:58
does the Gmat presents fractions in this way?
the majority of the time in this Qs I only had to make sure I wrote the equation right....
Intern
Intern
avatar
B
Joined: 10 Oct 2017
Posts: 13
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?  [#permalink]

Show Tags

New post 28 Oct 2018, 07:02
Eladt wrote:
does the Gmat presents fractions in this way?
the majority of the time in this Qs I only had to make sure I wrote the equation right....


I don't think GMAT would expect us to waste time in checking the question.
It'll be straightforward most of the time. Not to worry much about that.
GMAT Club Bot
Re: If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?   [#permalink] 28 Oct 2018, 07:02
Display posts from previous: Sort by

If 1/(x(x+1))+1/((x+1)(x+2))=1/(x+1), what is the value of x?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.