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What is the value of a  b ?
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15 Jan 2014, 01:50
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80% (00:32) correct 20% (00:42) wrong based on 651 sessions
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Re: What is the value of a  b ?
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15 Jan 2014, 01:50



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Re: What is the value of a  b ?
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15 Jan 2014, 23:50
Hi Bunuel,
I think that the second statement is (ab)² rather than (ab). Am I right?
Thanks.



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Re: What is the value of a  b ?
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16 Jan 2014, 00:52
The Question 37, Page 155 in Data Sufficiency Sample Questions of Quant Review is as follows:
What is the value of a  b ?
(1) \(a = b + 4\) (2) \((a  b)^2 = 16\)
Solution:
Statement (1)
\(a= b+4\) Or, \(ab=4\) As the value of ab can be uniquely determined, statement (1) is sufficient.
Statement (2)
Solving the equation, \((a  b)^2 = 16\), we have either \(ab= 4\) or \(ab= 4\). As the value of \(ab\) can not be uniquely determined, statement (2) is not sufficient.
Answer: (A)



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Re: What is the value of a  b ?
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18 Jan 2014, 03:59



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Re: What is the value of a  b ?
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18 Jan 2014, 13:49
Bunuel wrote: SOLUTION
What is the value of a  b ?
(1) a = b + 4 > rearrange: ab=4. Sufficient.
(2) (a  b)^2 = 16 > ab=4 or ab=4. Not sufficient.
Answer: A. how is 1 sufficient when a & b can still be any combination of numbers i.e. (0,4), (1,5) (2,6).....and on and on



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Re: What is the value of a  b ?
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19 Jan 2014, 09:36



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Re: What is the value of a  b ?
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27 Nov 2014, 06:23
Bunuel wrote: TroyfontaineMacon wrote: Bunuel wrote: SOLUTION
What is the value of a  b ?
(1) a = b + 4 > rearrange: ab=4. Sufficient.
(2) (a  b)^2 = 16 > ab=4 or ab=4. Not sufficient.
Answer: A. how is 1 sufficient when a & b can still be any combination of numbers i.e. (0,4), (1,5) (2,6).....and on and on Yes but we are asked to find the value of ab, not the individual values of a and b. Hi Bunuel, I have learnt from GMATClub that the root of a positive number is always positiveso root of 16 should only be 4 right (for GMAT purposes). Sothe answer should be D right?



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Re: What is the value of a  b ?
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27 Nov 2014, 06:27
KS15 wrote: Bunuel wrote: TroyfontaineMacon wrote: how is 1 sufficient when a & b can still be any combination of numbers i.e. (0,4), (1,5) (2,6).....and on and on
Yes but we are asked to find the value of ab, not the individual values of a and b. Hi Bunuel, I have learnt from GMATClub that the root of a positive number is always positiveso root of 16 should only be 4 right (for GMAT purposes). Sothe answer should be D right? The correct answer is A. When the GMAT provides the square root sign for an even root, such as a square root, fourth root, etc. then the only accepted answer is the positive root. That is: \(\sqrt{9} = 3\), NOT +3 or 3; \(\sqrt[4]{16} = 2\), NOT +2 or 2; Notice that in contrast, the equation \(x^2 = 9\) has TWO solutions, +3 and 3. Because \(x^2 = 9\) means that \(x =\sqrt{9}=3\) or \(x=\sqrt{9}=3\).
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Re: What is the value of a  b ?
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23 Mar 2017, 10:40
Is this really a 550level question? Looks like 400level one Just kidding......;
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Re: What is the value of a  b ? &nbs
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23 Mar 2017, 10:40






