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

It is currently 22 Oct 2019, 05:10

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

What is the range of values for z^2 given that (z^2+4)(z^2-2)<0

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

Hide Tags

Find Similar Topics 
Senior Manager
Senior Manager
User avatar
P
Status: Whatever it takes!
Joined: 10 Oct 2018
Posts: 383
GPA: 4
What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 19 Mar 2019, 05:17
4
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

43% (01:36) correct 57% (01:24) wrong based on 53 sessions

HideShow timer Statistics

What is the range of values for \(x^2\) given that (\(x^2\)+4)(\(x^2\)-2)<0?
(A) -4 < \(x^2\) < 2
(B) 0 ≤ \(x^2\) ≤ 2
(C) 0 ≤ \(x^2\) < 2
(D) 0 < \(x^2\) < 2
(E) -∞ < x < 2

_________________
Kudos OK Please!!

ALL ABOUT GMAT- \(https://exampal.com/gmat/blog/gmat-score-explained\)
GMAT Club Legend
GMAT Club Legend
User avatar
D
Joined: 18 Aug 2017
Posts: 5031
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
GMAT ToolKit User Premium Member
Re: What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 26 Mar 2019, 10:17
nm97 wrote:
What is the range of values for \(x^2\) given that (\(x^2\)+4)(\(x^2\)-2)<0?
(A) -4 < \(x^2\) < 2
(B) 0 ≤ \(x^2\) ≤ 2
(C) 0 ≤ \(x^2\) < 2
(D) 0 < \(x^2\) < 2
(E) -∞ < x < 2


basic clue or trick to solve this question is to check our desired outcome using given options
we need is (\(x^2\)+4)(\(x^2\)-2)<0
so x has to be <2 ; it cannot be =2 as then (\(x^2\)+4)(\(x^2\)-2)<0 wont stand true
so negate options A,B
also
value x^2 cannot be-ve so option E negated
between option C & D
we can note that (\(x^2\)+4)(\(x^2\)-2)<0 will hold true when x^2=0 so IMO C is correct :cool:
Intern
Intern
avatar
B
Joined: 18 Jan 2019
Posts: 28
Re: What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 26 Mar 2019, 23:28
Archit3110 wrote:
nm97 wrote:
What is the range of values for \(x^2\) given that (\(x^2\)+4)(\(x^2\)-2)<0?
(A) -4 < \(x^2\) < 2
(B) 0 ≤ \(x^2\) ≤ 2
(C) 0 ≤ \(x^2\) < 2
(D) 0 < \(x^2\) < 2
(E) -∞ < x < 2


basic clue or trick to solve this question is to check our desired outcome using given options
we need is (\(x^2\)+4)(\(x^2\)-2)<0
so x has to be <2 ; it cannot be =2 as then (\(x^2\)+4)(\(x^2\)-2)<0 wont stand true
so negate options A,B
also
value x^2 cannot be-ve so option E negated
between option C & D
we can note that (\(x^2\)+4)(\(x^2\)-2)<0 will hold true when x^2=0 so IMO C is correct :cool:


can you explain why A is wrong? the values in this range satisfy the condition
GMAT Club Legend
GMAT Club Legend
User avatar
D
Joined: 18 Aug 2017
Posts: 5031
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
GMAT ToolKit User Premium Member
What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 26 Mar 2019, 23:32
Ish1996 wrote:
Archit3110 wrote:
nm97 wrote:
What is the range of values for \(x^2\) given that (\(x^2\)+4)(\(x^2\)-2)<0?
(A) -4 < \(x^2\) < 2
(B) 0 ≤ \(x^2\) ≤ 2
(C) 0 ≤ \(x^2\) < 2
(D) 0 < \(x^2\) < 2
(E) -∞ < x < 2


basic clue or trick to solve this question is to check our desired outcome using given options
we need is (\(x^2\)+4)(\(x^2\)-2)<0
so x has to be <2 ; it cannot be =2 as then (\(x^2\)+4)(\(x^2\)-2)<0 wont stand true
so negate options A,B
also
value x^2 cannot be-ve so option E negated
between option C & D
we can note that (\(x^2\)+4)(\(x^2\)-2)<0 will hold true when x^2=0 so IMO C is correct :cool:


can you explain why A is wrong? the values in this range satisfy the condition


the range option A does not satisfy the inequality...
see we need a range where we get values<0 ; so substitute different values and you shall get the answer.
Intern
Intern
avatar
B
Joined: 18 Jan 2019
Posts: 28
Re: What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 26 Mar 2019, 23:50
Ish1996 wrote:
Archit3110 wrote:
nm97 wrote:
What is the range of values for \(x^2\) given that (\(x^2\)+4)(\(x^2\)-2)<0?
(A) -4 < \(x^2\) < 2
(B) 0 ≤ \(x^2\) ≤ 2
(C) 0 ≤ \(x^2\) < 2
(D) 0 < \(x^2\) < 2
(E) -∞ < x < 2


basic clue or trick to solve this question is to check our desired outcome using given options
we need is (\(x^2\)+4)(\(x^2\)-2)<0
so x has to be <2 ; it cannot be =2 as then (\(x^2\)+4)(\(x^2\)-2)<0 wont stand true
so negate options A,B
also
value x^2 cannot be-ve so option E negated
between option C & D
we can note that (\(x^2\)+4)(\(x^2\)-2)<0 will hold true when x^2=0 so IMO C is correct :cool:


can you explain why A is wrong? the values in this range satisfy the condition


Yeah you are right, I forgot about -2, thanks
Intern
Intern
avatar
B
Joined: 22 Sep 2018
Posts: 20
Re: What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 30 Mar 2019, 10:30
nm97 wrote:
What is the range of values for \(x^2\) given that (\(x^2\)+4)(\(x^2\)-2)<0?
(A) -4 < \(x^2\) < 2
(B) 0 ≤ \(x^2\) ≤ 2
(C) 0 ≤ \(x^2\) < 2
(D) 0 < \(x^2\) < 2
(E) -∞ < x < 2


In the equation (x^2 + 4)(x^2-2)<0..either (X^2 + 4) is negative or (x^2 - 2) is negative.

Clearly X^2+4 can never be negative. So X^2-2 is negative

X^2-2<0

x^2<2...only option C seems to agree with the equation
Manager
Manager
User avatar
S
Joined: 11 Feb 2013
Posts: 147
Location: Bangladesh
GMAT 1: 490 Q44 V15
GMAT 2: 690 Q47 V38
GPA: 3.05
WE: Analyst (Commercial Banking)
GMAT ToolKit User Premium Member Reviews Badge
What is the range of values for z^2 given that (z^2+4)(z^2-2)<0  [#permalink]

Show Tags

New post 30 Mar 2019, 11:33
Given, (x^2+4)(x^2-2)<0

So, in between (x^2+4) and (x^2-2), one expression must be positive and the other one must be negative.

Since x^2=a square value=always Non negative, (x^2+4) must be positive and (x^2-2) must be negative.

Thus, (x^2-2)<0
Or, x^2<2
So, x^2 must be less then 2 and since x^2 is a square value, it must be NON negative.

X^2 must be 0 or greater than 0 but less than 2.

My answer is C.

Posted from my mobile device
GMAT Club Bot
What is the range of values for z^2 given that (z^2+4)(z^2-2)<0   [#permalink] 30 Mar 2019, 11:33
Display posts from previous: Sort by

What is the range of values for z^2 given that (z^2+4)(z^2-2)<0

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





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