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If y^(3x) = 5^x and y is a positive number, what is x?

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If y^(3x) = 5^x and y is a positive number, what is x?  [#permalink]

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New post 24 Sep 2017, 23:56
1
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A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

59% (01:08) correct 41% (01:18) wrong based on 116 sessions

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Joined: 02 Jul 2017
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Concentration: Entrepreneurship, Technology
GMAT 1: 730 Q50 V38
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Re: If y^(3x) = 5^x and y is a positive number, what is x?  [#permalink]

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New post 25 Sep 2017, 03:03
1
If \(y^{3x}=5^x\) and y is a positive number, what is x?

\(y^{3x}=5^x\)
=> \((y^3)^x=5^x\)
=> \(y^3=5\)
=> \(y=5^\frac{1}{3}\)

(1) \(y= \sqrt[3]5\)
=> \(y^3 = 5\)
This is already given in question stem. As no detail about x given.
Insufficient

(2) \(y^x=5^\frac{x}{3}\)
=> \(y^x=(5^\frac{1}{3})^x\)
=> \(y=5^\frac{1}{3}\)
This is already given in question stem. As no detail about x given.
Insufficient

1+2
Here also we don't get any information about x

Answer: E
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Location: India
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Re: If y^(3x) = 5^x and y is a positive number, what is x?  [#permalink]

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New post 26 Feb 2018, 10:00
Nikkb wrote:
If \(y^{3x}=5^x\) and y is a positive number, what is x?

\(y^{3x}=5^x\)
=> \((y^3)^x=5^x\)
=> \(y^3=5\)
=> \(y=5^\frac{1}{3}\)

(1) \(y= \sqrt[3]5\)
=> \(y^3 = 5\)
This is already given in question stem. As no detail about x given.
Insufficient

(2) \(y^x=5^\frac{x}{3}\)
=> \(y^x=(5^\frac{1}{3})^x\)
=> \(y=5^\frac{1}{3}\)
This is already given in question stem. As no detail about x given.
Insufficient

1+2
Here also we don't get any information about x

Answer: E

Why can't we use the information given in the statement 1 and substitute it in the stem "y"??
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Re: If y^(3x) = 5^x and y is a positive number, what is x?  [#permalink]

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New post 26 Feb 2018, 10:45
sahilsnpt wrote:
Nikkb wrote:
If \(y^{3x}=5^x\) and y is a positive number, what is x?

\(y^{3x}=5^x\)
=> \((y^3)^x=5^x\)
=> \(y^3=5\)
=> \(y=5^\frac{1}{3}\)

(1) \(y= \sqrt[3]5\)
=> \(y^3 = 5\)
This is already given in question stem. As no detail about x given.
Insufficient

(2) \(y^x=5^\frac{x}{3}\)
=> \(y^x=(5^\frac{1}{3})^x\)
=> \(y=5^\frac{1}{3}\)
This is already given in question stem. As no detail about x given.
Insufficient

1+2
Here also we don't get any information about x

Answer: E

Why can't we use the information given in the statement 1 and substitute it in the stem "y"??


Hi sahilsnpt

our objective is to find the value of x and as explained in the above solution both statement 1 & the question stem gives the same information. So it will not lead to any solution. Just for practice, try substituting the value of y from statement 1 in the question stem and see if you are getting any value for x
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Joined: 19 Jun 2017
Posts: 56
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Re: If y^(3x) = 5^x and y is a positive number, what is x?  [#permalink]

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New post 27 Feb 2018, 12:15
niks18 wrote:
sahilsnpt wrote:
Nikkb wrote:
If \(y^{3x}=5^x\) and y is a positive number, what is x?

\(y^{3x}=5^x\)
=> \((y^3)^x=5^x\)
=> \(y^3=5\)
=> \(y=5^\frac{1}{3}\)

(1) \(y= \sqrt[3]5\)
=> \(y^3 = 5\)
This is already given in question stem. As no detail about x given.
Insufficient

(2) \(y^x=5^\frac{x}{3}\)
=> \(y^x=(5^\frac{1}{3})^x\)
=> \(y=5^\frac{1}{3}\)
This is already given in question stem. As no detail about x given.
Insufficient

1+2
Here also we don't get any information about x

Answer: E

Why can't we use the information given in the statement 1 and substitute it in the stem "y"??


Hi sahilsnpt

our objective is to find the value of x and as explained in the above solution both statement 1 & the question stem gives the same information. So it will not lead to any solution. Just for practice, try substituting the value of y from statement 1 in the question stem and see if you are getting any value for x

No,I am not getting any solution of X.Thank you for the explanation!
Re: If y^(3x) = 5^x and y is a positive number, what is x? &nbs [#permalink] 27 Feb 2018, 12:15
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