|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 20 Apr 2010
Posts: 227
Schools: ISB, HEC, Said
Followers: 4
Kudos [?]:
8
[1] , given: 28
|
What is the value of y? (1) 3|x^2 4| = y 2 (2) |3 y| = 11 [#permalink]
 29 Sep 2010, 08:33
1
This post received
KUDOS
Question Stats:
56% (01:56) correct
43% (00:54) wrong based on 3 sessions
What is the value of y? (1) 3|x^2 – 4| = y – 2 (2) |3 – y| = 11
|
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11506
Followers: 1791
Kudos [?]:
9526
[5] , given: 826
|
5
This post received
KUDOS
|
|
|
|
|
|
SVP
Joined: 05 Jul 2006
Posts: 1562
Followers: 4
Kudos [?]:
63
[1] , given: 32
|
Re: DS problem 3|x^2 – 4| = y – 2 [#permalink]
29 Sep 2010, 10:14
1
This post received
KUDOS
prashantbacchewar wrote: What is the value of y?
(1) 3|x^2 – 4| = y – 2
(2) |3 – y| = 11 from 1 equation with 2 unknown we can only deduct that y-2> 0 ie: y>2 from 2 y has to have 2 values +ve and -ve..........insuff both y>2 , then from 2 y has the +ve value. C
|
|
|
|
|
|
Manager
Joined: 03 Aug 2010
Posts: 248
Followers: 2
Kudos [?]:
27
[0], given: 41
|
Bunuel wrote: What is the value of y?
(1) 3|x^2 -4| = y - 2
(2) |3 - y| = 11
(1) As we are asked to find the value of y, from this statement we can conclude only that y\geq{2}, as LHS is absolute value which is never negative, hence RHS als can not be negative. Not sufficient.
(2) |3 - y| = 11:
y<3 --> 3-y=11 --> y=-8;
y\geq{3} --> -3+y=11 --> y=14.
Two values for y. Not sufficient.
(1)+(2) As from (1) y\geq{2}, then y=14. Sufficient.
Answer: C. Hey, pls explain the reasoning of LHS LHS is absolute value which is never negative, hence RHS als can not be negative.???
_________________
http://www.gmatpill.com/gmat-practice-test/
Amazing Platform
|
|
|
|
|
|
Manager
Joined: 01 Oct 2010
Posts: 71
Followers: 4
Kudos [?]:
44
[0], given: 19
|
hirendhanak wrote: Bunuel wrote: What is the value of y?
(1) 3|x^2 -4| = y - 2
(2) |3 - y| = 11
(1) As we are asked to find the value of y, from this statement we can conclude only that y\geq{2}, as LHS is absolute value which is never negative, hence RHS als can not be negative. Not sufficient.
(2) |3 - y| = 11:
y<3 --> 3-y=11 --> y=-8;
y\geq{3} --> -3+y=11 --> y=14.
Two values for y. Not sufficient.
(1)+(2) As from (1) y\geq{2}, then y=14. Sufficient.
Answer: C. Hey, pls explain the reasoning of LHS LHS is absolute value which is never negative, hence RHS als can not be negative.??? what values you can put for x? if you put x = 2, left hand side becomes zero, making y=2. if you put x as any other value, it will make 3*|x^2 - 4| positive, and add 2 to that, making y > 2. so, y is either 2 or greater. Hope this helps.
_________________
Some other posts by me...
My GMAT Journey
Timer Tool for Google spreadsheet
Quant Flash Cards/Pages
700 (Q:49 V:35) - Thanks GMATClub - Test Center experience
|
|
|
|
|
|
SVP
Status: 2000 posts! I don't know whether I should feel great or sad about it! LOL
Joined: 04 Oct 2009
Posts: 1756
Location: Peru
Schools: Harvard, Stanford, Wharton, MIT & HKS (Government)
WE 1: Economic research
WE 2: Banking
WE 3: Government: Foreign Trade and SMEs
Followers: 50
Kudos [?]:
145
[0], given: 108
|
Re: DS problem 3|x^2 – 4| = y – 2 [#permalink]
29 Oct 2010, 19:30
+1 C 
_________________
"Life’s battle doesn’t always go to stronger or faster men; but sooner or later the man who wins is the one who thinks he can."
My Integrated Reasoning Logbook / Diary: my-ir-logbook-diary-133264.html
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Intern
Joined: 05 Apr 2011
Posts: 11
Followers: 0
Kudos [?]:
1
[0], given: 0
|
I understand that this problem has already been solved. Still I can not comprehend why in the second equation we can have two values- both negative and positive when absolute value is opened, whereas it is stated that LHS is never negative in the first equation.
I will greatly appreciate if someone could elaborate on it.
5. What is the value of y?
(1) 3|x^2 -4| = y - 2
(2) |3 - y| = 11
Thank you guys,
Steve.
|
|
|
|
|
|
Senior Manager
Joined: 09 Feb 2011
Posts: 286
Concentration: General Management, Social Entrepreneurship
GMAT 1: 770 Q50 V47
Followers: 5
Kudos [?]:
88
[1] , given: 10
|
Re: Tricky question. [#permalink]
05 Apr 2011, 22:36
1
This post received
KUDOS
1st equation:
x^2 - 4 can be positive, or negative ( say x = 1, then x^2 - 4 is -3, and say x = 3, then x^2-4 is 5. However since its absolute value is taken, it will always be a positive number, which when multiplied by 3 will give either zero (if x=2) or a positive number. This added to 2 brought pver fom RHS of the equation will have to be a positive number still. So while Statement 1 is insufficient in telling us the value of y, it does tell us that y is positive.
Equation 2:
by telling us that absolute value of 3-y is 11 implies that the vlue inside the absolute value lines is either 11 or -11, which means that y is either 14 or -8. since it gives two values of y it is insufficient by itself.
However since statement tells us for certain that y i s positive and statement two give sus two values of y one positive and one negative, both combined we can pick the positive value and be sure that that is the correct value of y
hence both together ae sufficient
|
|
|
|
|
|
SVP
Joined: 16 Nov 2010
Posts: 1719
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 26
Kudos [?]:
227
[0], given: 34
|
Re: DS problem 3|x^2 – 4| = y – 2 [#permalink]
06 Apr 2011, 04:53
The answer is C. (1) says y is +ve, and (2) gives 2 values of y, one +ve and one -ve. So combining both we get y = 14.
_________________
Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Director
Joined: 01 Feb 2011
Posts: 792
Followers: 11
Kudos [?]:
62
[0], given: 42
|
Re: DS problem 3|x^2 – 4| = y – 2 [#permalink]
16 Apr 2011, 17:17
1. Insufficient
because all we know here is y>2
2. Insufficient.
because y can be -8 or 14
together . Sufficient.
Answer is C.
|
|
|
|
|
|
|
Re: DS problem 3|x^2 – 4| = y – 2
[#permalink]
16 Apr 2011, 17:17
|
|
|
|
|
|
|
|
|
|
|
close
