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If x is not equal to y and if x =y , what is the value of [#permalink]
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02 May 2011, 22:16
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If x is not equal to y and if \(\sqrt{x}=y\), what is the value of \(y^3\) ? (1) \(x = y^x\) (2) \(x^3 = 8\) can somebody explain how 1 is sufficient. i am getting confused...help
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Last edited by kamalkicks on 03 May 2011, 06:50, edited 1 time in total.



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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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02 May 2011, 23:02
b can be straightaway eliminated.However, it gives a possible value for x=2.which can be used to evaluate a. a. y = 2^(1/2) x = [2^(1/2)]^x x =2 is the only possible value apart from x=y=1. hence a.
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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03 May 2011, 06:34
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amit2k9 wrote: b can be straightaway eliminated.However, it gives a possible value for x=2.which can be used to evaluate a.
a. y = 2^(1/2) x = [2^(1/2)]^x
x =2 is the only possible value apart from x=y=1.
hence a. What if: \(y=\sqrt[3]{3}, \hspace{3} x=3\) OR \(y=\sqrt[4]{4}, \hspace{3} x=4\) In fact it will hold good for at least all integers > 1; \(y=\sqrt[n]{n}, \hspace{3} x=n\) Answer should be "C" in my opinion. Kamalkicks: Question reads: If x is not equal to y and if "IS SOMETHING MISSING", what is the value of y^3 ? Is there anything missing after second if?
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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03 May 2011, 06:50
fluke wrote: amit2k9 wrote: b can be straightaway eliminated.However, it gives a possible value for x=2.which can be used to evaluate a.
a. y = 2^(1/2) x = [2^(1/2)]^x
x =2 is the only possible value apart from x=y=1.
hence a. What if: \(y=\sqrt[3]{3}, \hspace{3} x=3\) OR \(y=\sqrt[4]{4}, \hspace{3} x=4\) In fact it will hold good for at least all integers > 1; \(y=\sqrt[n]{n}, \hspace{3} x=n\) Answer should be "C" in my opinion. Kamalkicks: Question reads: If x is not equal to y and if "IS SOMETHING MISSING", what is the value of y^3 ? Is there anything missing after second if? sorry... question corrected
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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04 May 2011, 04:39
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(1) x = y^x => y^2 = y^x => x = 2 => y^3 = (2)^3/2 Sufficient (2) X^3 = 8 => x = 2 => Y = (2)^3/2 Sufficient Answer  D
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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04 May 2011, 06:55
My answer is D.
Given Sqrt(x) = y => y ^3= x* Sqrt(x) = sqrt(x^3)
1. x = y ^x => y ^3= sqrt(x^3) =sqrt(y^(3x)) from this we can find x. Hence is sufficient to find y^3.
2.from this we can find x. Hence is sufficient to find y^3.
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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04 May 2011, 18:54
Hey subhashghosh Here is my interpretation of y. x = y^2. so x is +ve but the sign of y is unknown. Hence the value of y^3 is a black box now. Do you agree? S1 and S2 provide the same information. But the sign of y is unknown. So the answer should be E subhashghosh wrote: (1) x = y^x => y^2 = y^x
=> x = 2 => y^3 = (2)^3/2
Sufficient
(2)
X^3 = 8
=> x = 2 => Y = (2)^3/2 Sufficient Answer  D



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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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05 May 2011, 04:28
@gmat1220 we don't need to worry about sign of y, consider one more thing, if y is negative (y)^3/2 takes us in the realm of complex numbers, which is beyond the scope of GMAT.
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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05 May 2011, 19:15
kamalkicks wrote: If x is not equal to y and if \(\sqrt{x}=y\), what is the value of \(y^3\) ?
(1) \(x = y^x\)
(2) \(x^3 = 8\)
can somebody explain how 1 is sufficient. i am getting confused...help Try to connect the data in the question stem to the data given in the statement. Data in Question Stem: \(\sqrt{x}=y\) or \(x = y^2\) (I think of doing this because the statement gives the relation of 'x' with 'y', not of 'square root x' with 'y') (1) \(x = y^x\) or from above, \(y^2 = y^x\) Hence \(x = 2\) and \(y = \sqrt{2}\) Therefore, \(y^3 = (\sqrt{2})^3\) If logic confuses you, try and use simple algebra. Once you see it using algebra, reason it out to understand the concept well.
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Re: If x is not equal to y and if , what is the value of y^3 ? [#permalink]
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06 May 2011, 10:11
Karishma
y^3 can have two values i.e. 1.414^3 or 1.414^3, there has to be some constraint on y to get a single value of y^3. So is the answer D or E.



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If x is not equal to y and if √x = y, what is the value of y [#permalink]
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01 Apr 2012, 23:35
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If x is not equal to y and if √x = y, what is the value of y^3 ?
(1) x = y^x (2) x^3=8
Last edited by Bunuel on 01 Apr 2012, 23:54, edited 1 time in total.
Edited the question and added the OA



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Re: Exponents [#permalink]
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Re: If x is not equal to y and if √x = y, what is the value of y [#permalink]
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16 Jun 2015, 03:18
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Bunuel wrote: Smita04 wrote: if x is not equal to y and if √x = y, what is the value of y^3 ?
1) x = xy 2) x^3=8 Question should read: If x is not equal to y and if √x = y, what is the value of y^3 ? (1) x = y^x > since from \(\sqrt{x}=y\) we have that \(x=y^2\) then \(y^2=y^x\) > \(y=1\) or \(x=2\) (the first solutions is not valid since given that \(x\neq{y}\) and if \(y=1\) then \(x=y^2=1\) too). So, \(x=2\) > \(y=\sqrt{x}=\sqrt{2}\). Sufficient. (2) x^3=8 > \(x=2\) > \(y=\sqrt{x}=\sqrt{2}\). Sufficient. Answer: D. Where can I buy such mathematical lookthroughglasses? I need them desperately!!!!
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Re: If x is not equal to y and if √x = y, what is the value of y [#permalink]
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17 Jun 2015, 12:49
Bunuel wrote: Smita04 wrote: if x is not equal to y and if √x = y, what is the value of y^3 ?
1) x = xy 2) x^3=8 Question should read: If x is not equal to y and if √x = y, what is the value of y^3 ? (1) x = y^x > since from \(\sqrt{x}=y\) we have that \(x=y^2\) then \(y^2=y^x\) > \(y=1\) or \(x=2\) (the first solutions is not valid since given that \(x\neq{y}\) and if \(y=1\) then \(x=y^2=1\) too). So, \(x=2\) > \(y=\sqrt{x}=\sqrt{2}\). Sufficient. (2) x^3=8 > \(x=2\) > \(y=\sqrt{x}=\sqrt{2}\). Sufficient. Answer: D. To proof statement 1, would it be allowed to process as follows? What is the value of y^3? Since \(x = y^x\), we know that \(y^3=x\) and therefore \(x = 3\). If \(x =3\) then \(y^3=3\), which is sufficient. Any mistake in this?
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If x is not equal to y and if √x = y, what is the value of y [#permalink]
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17 Jun 2015, 12:56
reto wrote: To proof statement 1, would it be allowed to process as follows?
What is the value of y^3?
Since \(x = y^x\), we know that \(y^3=x\) and therefore \(x = 3\). If \(x =3\) then \(y^3=3\), which is sufficient.
Any mistake in this?
Hello retoFrom which part you infer that \(y^3=x\)? From this statement \(x = y^x\) we can't say that \(y^3=x\) because y and x can have infinite number of values x and y: x = 1 and y =1 x = 2 and y = \(\sqrt{2}\) x = 3 and y =cube root (3) and so on and only in first case (x =1 and y =1) your conclusion that \(y^3=x\) will be true
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Re: If x is not equal to y and if √x = y, what is the value of y [#permalink]
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17 Jun 2015, 13:05
Harley1980 wrote: reto wrote: To proof statement 1, would it be allowed to process as follows?
What is the value of y^3?
Since \(x = y^x\), we know that \(y^3=x\) and therefore \(x = 3\). If \(x =3\) then \(y^3=3\), which is sufficient.
Any mistake in this?
Hello retoFrom which part you infer that \(y^3=x\)? Because we have this equation here: x=y^x > if you plug y^3 on RHS you can infer that x = 3
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If x is not equal to y and if √x = y, what is the value of y [#permalink]
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17 Jun 2015, 13:09
reto wrote: Harley1980 wrote: reto wrote: To proof statement 1, would it be allowed to process as follows?
What is the value of y^3?
Since \(x = y^x\), we know that \(y^3=x\) and therefore \(x = 3\). If \(x =3\) then \(y^3=3\), which is sufficient.
Any mistake in this?
Hello retoFrom which part you infer that \(y^3=x\)? Because we have this equation here: x=y^x > if you plug y^3 on RHS you can infer that x = 3 But if we will follow to such logic then we can plug y^4 or y^5 and infer that x=4 or x=5 right? P.S. I am a little change my previous answer, please reread it.
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Re: If x is not equal to y and if √x = y, what is the value of y [#permalink]
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17 Jun 2015, 13:30
Harley1980 wrote:
But if we will follow to such logic then we can plug y^4 or y^5 and infer that x=4 or x=5 right?
P.S. I am a little change my previous answer, please reread it.
Harley1980 Well of course you are right. I have nothing more to say without my lawyer. Thank you. Good night
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If x is not equal to y and if √x = y, what is the value of y [#permalink]
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22 Jun 2016, 13:28
Question : y^3 = x^(3/2) = ? we need x to answer
(1) x=y^x, and from the question we know that x=y^2, so x=2, Sufficient
(2) x^3 = 8, x=2, Sufficient



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Re: If x is not equal to y and if √x = y, what is the value of y [#permalink]
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08 Sep 2017, 20:05
kamalkicks wrote: If x is not equal to y and if \(\sqrt{x}=y\), what is the value of \(y^3\) ?
(1) \(x = y^x\)
(2) \(x^3 = 8\)
can somebody explain how 1 is sufficient. i am getting confused...help Easy. Always try to simplify the stimulus manipulate the equations in their given form in a granular more clear way. \sqrt{x}=y  square both sides x=y^2 St 1 Substitute. Y^2=y^x suff St 2 X must be 2 there is no ambiguity since y is to an odd power D




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