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GMAT Diagnostic Test Question 44 [#permalink]
 07 Jun 2009, 01:12
GMAT Diagnostic Test Question 44Field: algebra Difficulty: 700
x^2 + y^2 = 100. All of the following could be true EXCEPT A. |x| + |y| = 10 B. |x| > |y| C. |x| > |y| + 10 D. |x| = |y| E. |x| - |y| = 5
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Last edited by dzyubam on 09 Nov 2009, 01:45, edited 4 times in total.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
14 Jun 2009, 09:26
Explanation
Official Answer: CA. |x| + |y| = 10 is possibl;e if one is 0 and the other is 10. B. |x| > |y| is possible if |x| > |5sqrt2| and |y| < |5sqrt2| C. |x| > |y| + 10 is never possible because if |x| > 10, (x^2+y2) becomes >100, which is wrong. D. |x| = |y| is possible if each is equal to |5sqrt2|. E. |x| - |y| = 5 is possible if if |x| = |9.11| and |y| = |4.11|. Therefore all but C are possible. |x| > |y| + 10 means x is greater than 10, which is not possible. So C is best.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
18 Jul 2009, 06:00
Correct the question please.
The answer choice says |x| > 0.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
18 Jul 2009, 11:23
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Re: GMAT Diagnostic Test Question 44 [#permalink]
18 Jul 2009, 22:13
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Re: GMAT Diagnostic Test Question 44 [#permalink]
18 Jul 2009, 23:39
Vishyan wrote: Correct the question please.
The answer choice says |x| > 0. The answer choices and question are little modified. Thanks for your suggestion. GT
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Re: GMAT Diagnostic Test Question 44 [#permalink]
20 Jul 2009, 08:17
2
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probably better to rephrase the question as, all of the following could be true EXCEPT
that phrasing seems to be much more common on standardized tests
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Re: GMAT Diagnostic Test Question 44 [#permalink]
29 Sep 2009, 04:41
GMAT TIGER wrote: Explanation
Official Answer: CA. |x| + |y| = 10 is possibl;e if one is 0 and the other is 10. B. |x| > |y| is possible if |x| > |5sqrt2| and |y| < |5sqrt2| C. |x| > |y| + 10 is never possible because if |x| > 10, (x^2+y2) becomes >100, which is wrong. D. |x| = |y| is possible if each is equal to |5sqrt2|. E. |x| - |y| = 5 is possible if if |x| = |9.11| and |y| = |4.11|. Therefore all but C are possible. |x| > |y| + 10 means x is greater than 10, which is not possible. So C is best. Hi GMAT TIGER, I don't quite understand some of the answers. The question stem states all of the following MUST be true, except 1. And if x^2 + y^2 = 100 then x=6 and y=8 is one potential solution as is x=0 and y=10. For statement a) |x| + |y| = 10 is only true if x=0 and y=10. But if x = 6 and y=8 then it wouldn't always be true? Maybe I'm missing something?
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Re: GMAT Diagnostic Test Question 44 [#permalink]
01 Oct 2009, 10:50
I agree.. dont think the wording of the sentence is correct. I dont think MUST should be in there.. maybe could
A does not have to be true
B does not have to be true
D does not have to be true
E does not have to be true
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Re: GMAT Diagnostic Test Question 44 [#permalink]
18 Oct 2009, 14:35
yangsta8 wrote: GMAT TIGER wrote: Explanation
Official Answer: CA. |x| + |y| = 10 is possibl;e if one is 0 and the other is 10. B. |x| > |y| is possible if |x| > |5sqrt2| and |y| < |5sqrt2| C. |x| > |y| + 10 is never possible because if |x| > 10, (x^2+y2) becomes >100, which is wrong. D. |x| = |y| is possible if each is equal to |5sqrt2|. E. |x| - |y| = 5 is possible if if |x| = |9.11| and |y| = |4.11|. Therefore all but C are possible. |x| > |y| + 10 means x is greater than 10, which is not possible. So C is best. Hi GMAT TIGER, I don't quite understand some of the answers. The question stem states all of the following MUST be true, except 1. And if x^2 + y^2 = 100 then x=6 and y=8 is one potential solution as is x=0 and y=10. For statement a) |x| + |y| = 10 is only true if x=0 and y=10. But if x = 6 and y=8 then it wouldn't always be true? Maybe I'm missing something? I agree here too - how come 5 ^ 2 + 5 ^ 2 = 100? Maybe I missed something - Unlike to see questions on GMAT with more than one answer
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Re: GMAT Diagnostic Test Question 44 [#permalink]
19 Oct 2009, 01:45
I used Pythagoras principle here:
let x and y be the sides of a triangle and 10 be the hypotenuse.
Now, A and C both are not possible.
A: sum of two sides cannot be equal to 10, the sum of two sides should be > 10.
C: x should be less than sum of y and 10.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
19 Oct 2009, 14:27
bb wrote: GMAT Diagnostic Test Question 44Field: algebra Difficulty: 700
x^2 + y^2 = 100. All of the following could be true EXCEPT A. |x| + |y| = 10 B. |x| > |y| C. |x| > |y| + 10 D. |x| = |y| E. |x| - |y| = 5 I guess rephrasing is necessary.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
07 Nov 2009, 08:11
Another vote for rephrasing from "must be true" to "is possible" 
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Re: GMAT Diagnostic Test Question 44 [#permalink]
09 Nov 2009, 03:52
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Re: GMAT Diagnostic Test Question 44 [#permalink]
21 Nov 2009, 09:12
GMAT TIGER wrote: Explanation
Official Answer: CA. |x| + |y| = 10 is possibl;e if one is 0 and the other is 10. B. |x| > |y| is possible if |x| > |5sqrt2| and |y| < |5sqrt2| C. |x| > |y| + 10 is never possible because if |x| > 10, (x^2+y2) becomes >100, which is wrong. D. |x| = |y| is possible if each is equal to |5sqrt2|. E. |x| - |y| = 5 is possible if if |x| = |9.11| and |y| = |4.11|.Therefore all but C are possible. |x| > |y| + 10 means x is greater than 10, which is not possible. So C is best. I have a hard time finding a way to prove E. How did you came up with the number?
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Re: GMAT Diagnostic Test Question 44 [#permalink]
22 Dec 2009, 06:02
lonewolf wrote: GMAT TIGER wrote: Explanation
Official Answer: CA. |x| + |y| = 10 is possibl;e if one is 0 and the other is 10. B. |x| > |y| is possible if |x| > |5sqrt2| and |y| < |5sqrt2| C. |x| > |y| + 10 is never possible because if |x| > 10, (x^2+y2) becomes >100, which is wrong. D. |x| = |y| is possible if each is equal to |5sqrt2|. E. |x| - |y| = 5 is possible if if |x| = |9.11| and |y| = |4.11|.Therefore all but C are possible. |x| > |y| + 10 means x is greater than 10, which is not possible. So C is best. I have a hard time finding a way to prove E. How did you came up with the number? Just solve the system of equations: x^2+y^2=100 x - y = 5 and you'll get the numbers to prove E.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
10 Feb 2010, 19:36
Igor010 wrote: Just solve the system of equations: x^2+y^2=100 x - y = 5 and you'll get the numbers to prove E. I don't think that'll work buddy: x - y = 5 x = y + 5, substitute into first eq yields: (y+5)^2 + y^2 = 100 rearranging gives: 2y^2 + 10y - 75 = 0.... there's no solution for the above: (check: b^2 - 4ac term is negative, which implies imaginary roots).
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Re: GMAT Diagnostic Test Question 44 [#permalink]
11 Feb 2010, 10:25
adalfu wrote: Igor010 wrote: Just solve the system of equations: x^2+y^2=100 x - y = 5 and you'll get the numbers to prove E. I don't think that'll work buddy: x - y = 5 x = y + 5, substitute into first eq yields: (y+5)^2 + y^2 = 100 rearranging gives: 2y^2 + 10y - 75 = 0.... there's no solution for the above: (check: b^2 - 4ac term is negative, which implies imaginary roots). I'm sorry adalfu, 2y^2+10y-75=0 gives us 100-(4*2*(-75)) which gives us +700. You can get square root and solve for Y. Even if you know approx. value of Y, you can find approx. value of X and then plug in to prove your results. Seems like you forgot to change the sign... Hope this helped.
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Re: GMAT Diagnostic Test Question 44 [#permalink]
11 Feb 2010, 10:55
doh! brilliant... thanks Igor010 i feel that all my quant errors are due to some sort of simple arithmetic mistakes (i'm a math/stats major but i've forgotten my basic algebra... sometimes i forget what 7x9 or 6x9 is -- i have to seriously think about it; it just doesn't come natural anymore). thanks
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Re: GMAT Diagnostic Test Question 44 [#permalink]
11 Feb 2010, 22:17
adalfu wrote: doh! brilliant... thanks Igor010 i feel that all my quant errors are due to some sort of simple arithmetic mistakes (i'm a math/stats major but i've forgotten my basic algebra... sometimes i forget what 7x9 or 6x9 is -- i have to seriously think about it; it just doesn't come natural anymore). thanks You're welcome! 
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Re: GMAT Diagnostic Test Question 44
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11 Feb 2010, 22:17
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