What is the value of x ? (1) x3 = 6x − x2 (2) 14x = x3 + 5 : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 20 Jan 2017, 08:46

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the value of x ? (1) x3 = 6x − x2 (2) 14x = x3 + 5

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

Hide Tags

Manager
Status: Still Struggling
Joined: 02 Nov 2010
Posts: 138
Location: India
GMAT Date: 10-15-2011
GPA: 3.71
WE: Information Technology (Computer Software)
Followers: 5

Kudos [?]: 80 [0], given: 8

What is the value of x ? (1) x3 = 6x − x2 (2) 14x = x3 + 5 [#permalink]

Show Tags

04 Oct 2011, 06:43
00:00

Difficulty:

(N/A)

Question Stats:

89% (01:36) correct 11% (00:00) wrong based on 9 sessions

HideShow timer Statistics

Please help me clarify one of the doubt that i have in the question below:

What is the value of x ?

(1) x3 = 6x − x2

(2) 14x = x3 + 5x2

1. Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
2. Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
3. Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
4. EITHER statement BY ITSELF is sufficient to answer the question.
5. Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, requiring more data pertaining to the problem.

-------------------------------------------------------------------------
Please see my doubt in the immediate post
[Reveal] Spoiler: OA

_________________

Appreciation in KUDOS please!
Knewton Free Test 10/03 - 710 (49/37)
Princeton Free Test 10/08 - 610 (44/31)
Kaplan Test 1- 10/10 - 630
Veritas Prep- 10/11 - 630 (42/37)
MGMAT 1 - 10/12 - 680 (45/34)

Manager
Status: Still Struggling
Joined: 02 Nov 2010
Posts: 138
Location: India
GMAT Date: 10-15-2011
GPA: 3.71
WE: Information Technology (Computer Software)
Followers: 5

Kudos [?]: 80 [0], given: 8

Re: What is a value of X [#permalink]

Show Tags

04 Oct 2011, 06:48
The explaination that has been given is not wrong. But i solved this question through another method and got C as an ans..

We can solve each of the equation and get following roots:
From 1 : 2, -3
From 2 : 2, -7

i got the above roots by diving the RHS and LHS by x to eliminate one x from both the equations. What the OE is given is that they solved this question WITHOUT eliminating the x and hence got X=0 as another solution. Hence, instead of a single solution of x=2, they got 2 common solutions, i.e. x=0 and x=2.

My doubt is that since my maths days in junior school, it has been taught to divide and remove any redundant data. thats what i did. What's wrong in my approach??
_________________

Appreciation in KUDOS please!
Knewton Free Test 10/03 - 710 (49/37)
Princeton Free Test 10/08 - 610 (44/31)
Kaplan Test 1- 10/10 - 630
Veritas Prep- 10/11 - 630 (42/37)
MGMAT 1 - 10/12 - 680 (45/34)

Manager
Joined: 20 Aug 2011
Posts: 146
Followers: 3

Kudos [?]: 95 [0], given: 0

Re: What is a value of X [#permalink]

Show Tags

04 Oct 2011, 06:53
krishnasty wrote:
The explaination that has been given is not wrong. But i solved this question through another method and got C as an ans..

We can solve each of the equation and get following roots:
From 1 : 2, -3
From 2 : 2, -7

i got the above roots by diving the RHS and LHS by x to eliminate one x from both the equations. What the OE is given is that they solved this question WITHOUT eliminating the x and hence got X=0 as another solution. Hence, instead of a single solution of x=2, they got 2 common solutions, i.e. x=0 and x=2.

My doubt is that since my maths days in junior school, it has been taught to divide and remove any redundant data. thats what i did. What's wrong in my approach??

x can be zero in both statements. you ignored that value. the question doesn't state any data (such as x is positive) that suggests that 0 is not a possible option.

clear?
_________________

Hit kudos if my post helps you.
You may send me a PM if you have any doubts about my solution or GMAT problems in general.

Intern
Joined: 17 Dec 2010
Posts: 13
Schools: ISB
Followers: 0

Kudos [?]: 4 [0], given: 2

Re: What is a value of X [#permalink]

Show Tags

04 Oct 2011, 07:02
You haven't considered 0 as a possible answer

Statement 1 => x= 0 or 2 or -3
Statement 2 => x= 0 or -7 or 2

Thus even when statements 1 and 2 are taken together => x can still be either 0 or 2 -> which is not sufficient.
Answer - (E)
Manager
Status: Still Struggling
Joined: 02 Nov 2010
Posts: 138
Location: India
GMAT Date: 10-15-2011
GPA: 3.71
WE: Information Technology (Computer Software)
Followers: 5

Kudos [?]: 80 [0], given: 8

Re: What is a value of X [#permalink]

Show Tags

04 Oct 2011, 07:30
braxus wrote:
You haven't considered 0 as a possible answer

Statement 1 => x= 0 or 2 or -3
Statement 2 => x= 0 or -7 or 2

Thus even when statements 1 and 2 are taken together => x can still be either 0 or 2 -> which is not sufficient.
Answer - (E)

I am not sure if you got my doubt..i understand that 0 can also be a possibility but when u approach the question, it's general tendency to cancel out x from both side of the equations. and I KNOW that it's not incorrect. And if you solve by cancelling out the Xs from the equations, u wont get 0 as a solution..
_________________

Appreciation in KUDOS please!
Knewton Free Test 10/03 - 710 (49/37)
Princeton Free Test 10/08 - 610 (44/31)
Kaplan Test 1- 10/10 - 630
Veritas Prep- 10/11 - 630 (42/37)
MGMAT 1 - 10/12 - 680 (45/34)

Manager
Joined: 20 Aug 2011
Posts: 146
Followers: 3

Kudos [?]: 95 [0], given: 0

Re: What is a value of X [#permalink]

Show Tags

04 Oct 2011, 07:49
you cancel out x only when you know that x is not zero,
_________________

Hit kudos if my post helps you.
You may send me a PM if you have any doubts about my solution or GMAT problems in general.

Re: What is a value of X   [#permalink] 04 Oct 2011, 07:49
Similar topics Replies Last post
Similar
Topics:
What is the value of x? (1) |x| = 3 (2) x = |3| 1 01 Dec 2016, 01:01
3 If 3x + 2z = 34, what is the value of z? (1) x3 = 64 (2) 5x = z + 9 4 04 Apr 2016, 06:18
1 If -3/4*x+3y-1/2=3/2*y-1/4*x what is the value of x? 3 28 Jan 2011, 04:10
1 What is the value of X^5? (1) X^2 = 9 (2) X^3 >9 2 26 Oct 2010, 06:52
20 Seven integers, x1, x2, x3, x4, x5, x6, and x7, are picked 13 04 Dec 2008, 12:31
Display posts from previous: Sort by

What is the value of x ? (1) x3 = 6x − x2 (2) 14x = x3 + 5

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

 Powered by phpBB © phpBB Group and phpBB SEO 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®.