Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 04 May 2015, 22:17

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# absolute

Author Message
TAGS:
SVP
Joined: 05 Jul 2006
Posts: 1519
Followers: 5

Kudos [?]: 115 [0], given: 39

absolute [#permalink]  04 Dec 2006, 05:18
SOLVE FOR X

1) l x+1 l / x-2 l <3

2) l n+2 / n l >=4

i will highly appreciate detailed conceptual answers
SVP
Joined: 01 May 2006
Posts: 1805
Followers: 8

Kudos [?]: 99 [0], given: 0

Re: absolute [#permalink]  04 Dec 2006, 08:35
2) l n+2 / n l >=4

It's more solving for n than for x, here

| n+2 / n | >=4
<=> |n+2| / |n| >=4
<=> |n+2| >= 4*|n| as |n| >= 0
<=> |n+2| - 4*|n| >= 0

o If n > 0 then the inequation becomes:
n+2 - 4*n >= 0
<=> n <= 2/3
=> 0 < n <= 2/3

o If -2 < n < 0 then the inequation becomes:
n+2 - 4*(-n) >= 0
<=> n >= -2/5
=> -2/5 <= n < 0

o If n < -2 then the inequation becomes:
-(n+2) - 4*(-n) >= 0
<=> n >= 2/3
Impossible.... no values for n here.

Finally, we have:
o 0 < n <= 2/3
or
o -2/5 <= n < 0
Senior Manager
Joined: 23 May 2005
Posts: 266
Location: Sing/ HK
Followers: 1

Kudos [?]: 19 [0], given: 0

we don't need to even solve for n because question stem is asking for value of x. so 2 is automatically insuff. we only look at statement 1
_________________

Impossible is nothing

SVP
Joined: 01 May 2006
Posts: 1805
Followers: 8

Kudos [?]: 99 [0], given: 0

Hermione wrote:
we don't need to even solve for n because question stem is asking for value of x. so 2 is automatically insuff. we only look at statement 1

Following previous post of Yezz, I understand it more as 2 independent excercices .... and not a DS .... A bit like in this thread : http://www.gmatclub.com/phpbb/viewtopic.php?p=274350

Maybe, I'm wrong.... Let Yezz clarifies it
Senior Manager
Joined: 23 May 2005
Posts: 266
Location: Sing/ HK
Followers: 1

Kudos [?]: 19 [0], given: 0

Okie
_________________

Impossible is nothing

SVP
Joined: 05 Jul 2006
Posts: 1519
Followers: 5

Kudos [?]: 115 [0], given: 39

FIG is on target here, sorry folks for confusion , i was sending this in a hurry during mu lunch break, thanks FIG and Hermoine, a million
Senior Manager
Joined: 23 May 2005
Posts: 266
Location: Sing/ HK
Followers: 1

Kudos [?]: 19 [0], given: 0

Fig, i know i'm going back to basics here...

In this problem, how did you know to test for:

(1) n>o
(2) -2 < n < 0
(3) n < -2

Normally for a problem like this, I would just test for n>0 or n<0 but apparently this is not the case.
_________________

Impossible is nothing

SVP
Joined: 01 May 2006
Posts: 1805
Followers: 8

Kudos [?]: 99 [0], given: 0

Hermione wrote:
Fig, i know i'm going back to basics here...

In this problem, how did you know to test for:

(1) n>o
(2) -2 < n < 0
(3) n < -2

Normally for a problem like this, I would just test for n>0 or n<0 but apparently this is not the case.

Any question has always to be asked , especially before going to an exam such as the GMAT ... and u are welcome

Concerning the reason, the principle is to look for the crucial "point" or value s of n,x... when those values make flip the sign of the expression in the absolute value. This is done for every absolute values of an inequation.

Concretely, we decompose the whole inquation in module to study:
o |n+2|:
# n+2 = 0 <=> n = -2

Also,
# n+2 > 0 <=> n > -2
# n+2 < 0 <=> n < -2

> The original inequation has to be studied on those 2 domains n < -2 and n > -2. Indeed, for those 2 domains, the simplified expression of |n+2| differs. That is |n+2| = n+2 when n > -2 and |n+2| = -(n+2) when n < -2.

o |n|:
# n = 0

Thus,
# n > 0
# n < 0

Finally, we have to study all combined domains, from |n+2| and from |n|, in the original inequation.

That gives : n < -2, -2 < n < 0, and n > 0.
Senior Manager
Joined: 23 May 2005
Posts: 266
Location: Sing/ HK
Followers: 1

Kudos [?]: 19 [0], given: 0

Thanks so much for explaining Fig!!! That was a bit complicated... But I think I got it... Can you suggest any sites where I can brush up on absolute value fundamentals?
_________________

Impossible is nothing

Similar topics Replies Last post
Similar
Topics:
Absolute inequality with multiple absolutes 1 20 Dec 2013, 09:19
Absolute 4 06 Apr 2007, 17:24
ABSOLUTE 3 02 Dec 2006, 03:10
Absolute Value? 4 29 May 2006, 22:54
Absolut Valu 5 23 Oct 2005, 06:34
Display posts from previous: Sort by