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M06-06

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M06-06 [#permalink]

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New post 16 Sep 2014, 00:27
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If \(y(u - c) = 0\) and \(j(u - k) = 0\), which of the following must be true, assuming \(c \lt k\)?

A. \(yj \lt 0\)
B. \(yj \gt 0\)
C. \(yj = 0\)
D. \(j = 0\)
E. \(y = 0\)

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Re M06-06 [#permalink]

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New post 16 Sep 2014, 00:27
Official Solution:

If \(y(u - c) = 0\) and \(j(u - k) = 0\), which of the following must be true, assuming \(c \lt k\)?

A. \(yj \lt 0\)
B. \(yj \gt 0\)
C. \(yj = 0\)
D. \(j = 0\)
E. \(y = 0\)


\(y(u - c) = 0\). Either \(u=c\) or \(y=0\);

\(j(u - k) = 0\). Either \(u=k\) or \(j=0\);

Now, the first option (\(u=c\) and \(u=k\)) cannot be simultaneously correct for both equations because if it is, then it would mean that \(u=c=k\), but we are given that \(c \lt k\). So, only one can be correct so either \(y=0\) or \(j=0\), which makes \(yj = 0\) always true.


Answer: C
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Collection of Questions:
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Re: M06-06 [#permalink]

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New post 12 Sep 2016, 12:43
Thanks for the explanation. Somehow I missed to guess the logic of u=c and u=k can't happen simultaneously.
And got this wrong. The explanation is crisp and concise.
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Re: M06-06 [#permalink]

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New post 26 Dec 2017, 20:39
Hello Bunuel,
besides the fact that c<k, can't it be "and/or" instead of "or" for each assumption?
y(u−c)=0. Either u=c AND/or y=0? It doesn't change the answer but I would like to know why you didn't include it in your solution. Thank you
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Re: M06-06 [#permalink]

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New post 26 Dec 2017, 21:01
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Guimeister wrote:
Hello Bunuel,
besides the fact that c<k, can't it be "and/or" instead of "or" for each assumption?
y(u−c)=0. Either u=c AND/or y=0? It doesn't change the answer but I would like to know why you didn't include it in your solution. Thank you


Yes it's an inclusive OR, which means that Either \(u=c\) or \(y=0\) (or both).
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
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Re: M06-06   [#permalink] 26 Dec 2017, 21:01
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