Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 20 Mar 2015
Posts: 62

Re: What is the value of y? [#permalink]
Show Tags
06 May 2016, 21:47
Bunuel wrote: What is the value of y?
(1) \(3x^24=y2\). Now, since 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 cannot be negative. Not sufficient.
(2) \(3  y = 11\):
\(y<3\) > \(3y=11\) > \(y=8\); \(y\geq{3}\) > \(3+y=11\) > \(y=14\).
Two values for \(y\). Not sufficient.
(1)+(2) Since from (1) \(y\geq{2}\), then from (2) \(y=14\). Sufficient.
Answer: C.
Hope it's clear. Why is Y>=0? Can't we write 'Y>0'? If LHS is positive and RHS must also be positive then, RHS has to be greater than 0. As 0 is neither positive nor negative, how can we write Y>=0? some value= some value. Since LHS is an absolute value, RHS has to be positive as well. Why is RHS>=0 and not RHS>0?



Math Expert
Joined: 02 Aug 2009
Posts: 5721

Re: What is the value of y? [#permalink]
Show Tags
06 May 2016, 22:12
shekhar4847 wrote: Bunuel wrote: What is the value of y?
(1) \(3x^24=y2\). Now, since 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 cannot be negative. Not sufficient.
(2) \(3  y = 11\):
\(y<3\) > \(3y=11\) > \(y=8\); \(y\geq{3}\) > \(3+y=11\) > \(y=14\).
Two values for \(y\). Not sufficient.
(1)+(2) Since from (1) \(y\geq{2}\), then from (2) \(y=14\). Sufficient.
Answer: C.
Hope it's clear. what if y is between 2 and 3? In that case we will have two values of y. Could you please clarify? Hi shekhar4847, I gives you \(y\geq{2}\)... II gives you two cases.. a) \(y<3\) > \(3y=11\) > \(y=8\); this means if y<3, it can have ONLY 8 as the value, so when we combine this with \(y\geq{2}\),which does not fit between 2 and 3.. hence WRONG b)\(y\geq{3}\) > \(3+y=11\) > \(y=14\) this means if \(y\geq{3}\), it can have ONLY 14 as the value, so when we combine this with \(y\geq{2}\), 14 fits in both the ranges.. hence CORRECT
_________________
Absolute modulus :http://gmatclub.com/forum/absolutemodulusabetterunderstanding210849.html#p1622372 Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
GMAT online Tutor



Math Expert
Joined: 02 Aug 2009
Posts: 5721

Re: What is the value of y? [#permalink]
Show Tags
06 May 2016, 22:15
bimalr9 wrote: Bunuel wrote: What is the value of y?
(1) \(3x^24=y2\). Now, since 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 cannot be negative. Not sufficient.
(2) \(3  y = 11\):
\(y<3\) > \(3y=11\) > \(y=8\); \(y\geq{3}\) > \(3+y=11\) > \(y=14\).
Two values for \(y\). Not sufficient.
(1)+(2) Since from (1) \(y\geq{2}\), then from (2) \(y=14\). Sufficient.
Answer: C.
Hope it's clear. Why is Y>=0? Can't we write 'Y>0'? If LHS is positive and RHS must also be positive then, RHS has to be greater than 0. As 0 is neither positive nor negative, how can we write Y>=0? some value= some value. Since LHS is an absolute value, RHS has to be positive as well. Why is RHS>=0 and not RHS>0? Hi, an ABSOLUTE value is NOT necessarily positive, it is NONNEGATIVE, so it can include both 0 and +ive value.. if in statement I x is 2 or 2, LHS will be 0 and hence y=2..
_________________
Absolute modulus :http://gmatclub.com/forum/absolutemodulusabetterunderstanding210849.html#p1622372 Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
GMAT online Tutor



Moderator
Joined: 22 Jun 2014
Posts: 998
Location: India
Concentration: General Management, Technology
GPA: 2.49
WE: Information Technology (Computer Software)

Re: What is the value of y? [#permalink]
Show Tags
07 May 2016, 01:49
dvinoth86 wrote: What is the value of y? (1) 3x^2 – 4 = y – 2 (2) 3 – y = 11 Y = ? stmt:1  it has two variables X AND Y. we need value of Y. insuff. stmt:2  Y=8 or Y=11 insuff. combined:  frm stmt1 3x^2 – 4 = y – 2 X^2 is positive. value of mod is positive. so left hand side is POSITIVE. frm stmt2 Y=8 or Y=11 so we can only pick 11 as the value to keep right hand side POSITIVE. Option C is right.
_________________
 Target  720740 http://gmatclub.com/forum/informationonnewgmatesrreportbeta221111.html http://gmatclub.com/forum/listofoneyearfulltimembaprograms222103.html



Intern
Joined: 11 Sep 2015
Posts: 8

What is the value of y? [#permalink]
Show Tags
14 Aug 2016, 01:44
Hi Bunuel, Please correct me if i am wrong. i). 3x^2  4 =y2 3x^2 = y+ 10 OR 3x^2 = y +14 equating the 2 values of 3x^2 Cant we equate these 2 values?y=10 = y +14 y=2 ii). gives 2 values of y 8 & 14 therefore, answer is A



Board of Directors
Status: Stepping into my 10 years long dream
Joined: 18 Jul 2015
Posts: 3235

Re: What is the value of y? [#permalink]
Show Tags
14 Aug 2016, 02:39
shrashtisinghal wrote: Hi Bunuel, Please correct me if i am wrong. i). 3x^2  4 =y2 3x^2 = y+ 10 OR 3x^2 = y +14 equating the 2 values of 3x^2 Cant we equate these 2 values?y=10 = y +14 y=2 ii). gives 2 values of y 8 & 14 therefore, answer is A How do you know that we have 3x^2  12 =y2 or 12  3x^2 =y2 Since, we donot know which of the above equations is valid. We cannot deduce a single value. As per Modulus property, Mod(x) = x if x>0 = x if x<0. Hence A is not sufficient. In B also, we are getting two values of y, so not sufficient. But, when you combine the statements, you will see the equation is satisfied only for y =14. hence, C.
_________________
How I improved from V21 to V40! ? How to use this forum in THE BEST way?



Retired Moderator
Joined: 05 Jul 2006
Posts: 1741

Re: What is the value of y? [#permalink]
Show Tags
18 Oct 2016, 00:52
dvinoth86 wrote: What is the value of y?
(1) 3x^2 – 4 = y – 2 (2) 3 – y = 11 FROM 1 (y2)/3 >= 0 , thus y>= 2 ... ... insuff from 2 3y = 11 or 3y = 11 , thus Y could be either 8 or 14.. insuff both together since from 1 y>= 2 and from 2 y = 8 or 14 then y = 4 ( common domain) ...C



Intern
Joined: 26 Feb 2015
Posts: 31
Location: Thailand
Concentration: Entrepreneurship, Strategy
GMAT 1: 630 Q49 V27 GMAT 2: 680 Q48 V34
GPA: 2.92
WE: Supply Chain Management (Manufacturing)

Re: What is the value of y? [#permalink]
Show Tags
14 Aug 2017, 21:32
Bunuel wrote: What is the value of y?
(1) \(3x^24=y2\). Now, since 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 cannot be negative. Not sufficient.
(2) \(3  y = 11\):
\(y<3\) > \(3y=11\) > \(y=8\); \(y\geq{3}\) > \(3+y=11\) > \(y=14\).
Two values for \(y\). Not sufficient.
(1)+(2) Since from (1) \(y\geq{2}\), then from (2) \(y=14\). Sufficient.
Answer: C.
Hope it's clear. Brilliant approach! I'd never thought it could be this easy.



Manager
Joined: 21 Jul 2017
Posts: 96
Location: India
Concentration: Social Entrepreneurship, Leadership
GPA: 4

Re: What is the value of y? [#permalink]
Show Tags
22 Sep 2017, 10:22
Me: Hi Bunuel, I am facing trouble with inequalities and modulus questions. Could you please suggest links, books to get good hold on on these topics? Thank you! Bunuel: Hi, 9. Inequalities For more check Ultimate GMAT Quantitative Megathread Hope it helps. Regards, Bunuel. P.S. Please post questions directly on the forum instead of pming. Thank you.[/quote]Me: Thanks a ton! (Posted it directly on the forum, Not pming )




Re: What is the value of y?
[#permalink]
22 Sep 2017, 10:22



Go to page
Previous
1 2 3
[ 49 posts ]



