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

 It is currently 03 Jul 2015, 19:23

### 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

# Is x negative ? (1) n^3(1-x^2)<0 (2) x^2-1<0

Author Message
TAGS:
Manager
Joined: 28 Jun 2005
Posts: 217
Followers: 1

Kudos [?]: 3 [0], given: 0

Is x negative ? (1) n^3(1-x^2)<0 (2) x^2-1<0 [#permalink]  14 Sep 2005, 08:12
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Is x negative ?
(1) n^3(1-x^2)<0
(2) x^2-1<0
VP
Joined: 22 Aug 2005
Posts: 1120
Location: CA
Followers: 1

Kudos [?]: 46 [0], given: 0

I will think its E.

i) n^3 (1- x^2) < 0
not sufficient unless we know n.

ii) x^2 < 1 or mod(x) < 1
-1<x<+1

not sufficient

together:
n^3 (1- x^2) < 0

if:
n < 0 and x < 0 (but > -1)
n < 0 and x > 0 (but < 1)

PS: is it n^3 or x^3?
Senior Manager
Joined: 30 Oct 2004
Posts: 286
Followers: 1

Kudos [?]: 16 [0], given: 0

I'm getting E

1) Insuff
n^3(1-x^2)<0
n^3<0 or 1-x^2<0
n^3<0 or x^2>1
or n is negative and x could be -ve or +ve integer or fraction>1

2) Insuff
x^2-1<0
or x^2<1
x could be a -ve or +ve fraction.

1 & 2) just proves 1-x^2>0 or x is a fraction either +ve or -ve. insuff
_________________

-Vikram

Intern
Joined: 19 Aug 2005
Posts: 41
Followers: 0

Kudos [?]: 1 [0], given: 0

i am getting E too

Intern
Joined: 14 Jun 2005
Posts: 37
Followers: 1

Kudos [?]: 2 [0], given: 0

My take is C.

stem 1: n^3(1-x^2)<0
i.e. either n^3<0 or (1-x^2)<0. Not sufficient.

stem 2: x^2-1<0 = x^2<1. Not sufficient.

Now lets combine both the statements:-
According to stem 2: x^2 is less than 1 which means 1-x^2 is +ve. Therefore n^3 should be -ve [according to stem 1]. Thus both the statements taken together are sufficient to ans the question.

Lemme know if i am missing somehting in my approach.
VP
Joined: 13 Jun 2004
Posts: 1119
Location: London, UK
Schools: Tuck'08
Followers: 7

Kudos [?]: 31 [0], given: 0

tingle wrote:
My take is C.

stem 1: n^3(1-x^2)<0
i.e. either n^3<0 or (1-x^2)<0. Not sufficient.

stem 2: x^2-1<0 = x^2<1. Not sufficient.

Now lets combine both the statements:-
According to stem 2: x^2 is less than 1 which means 1-x^2 is +ve. Therefore n^3 should be -ve [according to stem 1]. Thus both the statements taken together are sufficient to ans the question.

Lemme know if i am missing somehting in my approach.

The question is wether X is negative or not. I think you thought the question was concerning N.

X can be -ive or +ive, even in your example

x^2 is less than 1 so -1<x<1
Senior Manager
Joined: 14 Apr 2005
Posts: 418
Location: India, Chennai
Followers: 1

Kudos [?]: 6 [0], given: 0

From statement 1, x could be both +ve or -ve
Similarly from statement 2 could be both + ve or -ve,

And combing both statements will also not be sufficient.
Intern
Joined: 14 Jun 2005
Posts: 37
Followers: 1

Kudos [?]: 2 [0], given: 0

Antmavel wrote:
tingle wrote:
My take is C.

stem 1: n^3(1-x^2)<0
i.e. either n^3<0 or (1-x^2)<0. Not sufficient.

stem 2: x^2-1<0 = x^2<1. Not sufficient.

Now lets combine both the statements:-
According to stem 2: x^2 is less than 1 which means 1-x^2 is +ve. Therefore n^3 should be -ve [according to stem 1]. Thus both the statements taken together are sufficient to ans the question.

Lemme know if i am missing somehting in my approach.

The question is wether X is negative or not. I think you thought the question was concerning N.

X can be -ive or +ive, even in your example

x^2 is less than 1 so -1<x<1

Ooops.. I misunderstood the question! thanks antmavel for the clarification.
Senior Manager
Joined: 15 Aug 2005
Posts: 257
Location: Las Vegas, NV
Followers: 2

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

I get E as well. Combining the statements gets you + and - possibilities.
Similar topics Replies Last post
Similar
Topics:
Is x negative? 1) x^3(1-x^2)<0 2) x^2-1<0 1 15 Aug 2009, 23:45
1 Is x negative? 1) x^3(1-x^2)<0 2) x^2-1<0 4 21 Jun 2009, 17:59
Is x negative? 1) x^3(1-x^2) < 0 2) x^2 - 1 < 0 2 08 Jun 2009, 22:24
1 Is x negative? 1. x^3(1-x^2)<0 2. x^2-1<0 9 17 Jun 2008, 18:05
Is x negative? (1) x^3(1-x^2) < 0 (2) x^2 - 1 < 0 10 23 Aug 2007, 18:12
Display posts from previous: Sort by