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# 2^(x+y)/2^(x-y)=?

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Re: 2^(x+y)/2^(x-y)=? [#permalink]
Solve the stem - you will get 2^2y
Hence B
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Re: 2^(x+y)/2^(x-y)=? [#permalink]
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if GMAT will ask such questions then I'll score 800.

Sent from my iPhone using GMAT Club Forum mobile app
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Re: 2^(x+y)/2^(x-y)=? [#permalink]
MathRevolution wrote:
2^(x+y)/2^(x-y)=?
1) x=1
2) y=2

*An answer will be posted in 2 days

2^(x+y)/2^(x-y)= 2^(x+y)- (x-y)= 2^2y

So, it depends on the value of y.

B is the answer
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Re: 2^(x+y)/2^(x-y)=? [#permalink]
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MathRevolution wrote:
2^(x+y)/2^(x-y)=?

1) x=1
2) y=2

Target question: What is the value of 2^(x+y)/2^(x-y)?
This is a great candidate for rephrasing the target question.

Let's apply the division law, (x^a)/(x^b) = x^(a-b)
So, 2^(x+y)/2^(x-y) = 2^[(x+y) - (x-y)]
= 2^(2y)

We can now REPHRASE the target question...
REPHRASED target question: What is the value of 2^(2y)?

Statement 1: x = 1
This information has no bearing on the REPHRASED target question
So, statement 1 is NOT SUFFICIENT

Statement 2: y = 2
PERFECT.
This means that 2^(2y) = 2^4 = 16
Since we can answer the REPHRASED target question with certainty, statement 2 is SUFFICIENT

Answer =

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Re: 2^(x+y)/2^(x-y)=? [#permalink]
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If we modify the original condition and the question, we get 2^(x+y)/2(x-y)=? --> 2^((x+y)-(x-y))=2^2y. We only have to know y and the correct answer is B.

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
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2^x+y/2^x-y=? [#permalink]
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$$2^x^+^y/2^x^-^y=?$$

1) x=1
2) y=2
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Re: 2^x+y/2^x-y=? [#permalink]
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MathRevolution wrote:
$$2^x^+^y/2^x^-^y=?$$

1) x=1
2) y=2

$$2^x^+^y/2^x^-^y=\frac{2^x*2^y}{2^x}*2^y=2^{2y}$$

So we require to know only y..

Statement II gives us value of y..
Sufficient

B
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2^x+y/2^x-y=? [#permalink]
MathRevolution wrote:
$$2^x^+^y/2^x^-^y=?$$

1) x=1
2) y=2

2^(x+y-(x-y))----{ as x^m/x^n = X^(m-n)}
=2^(x+y-x+y)
=2^2y=??

(1) x=1
no info on Y
insuff

(2) y=2
thus 2^2y = 2^4 =16
suff

Ans B
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Re: 2^x+y/2^x-y=? [#permalink]
MathRevolution wrote:
$$2^x^+^y/2^x^-^y=?$$

1) x=1
2) y=2

2^(x+y-x+y)=2^2y
A-not suff
B-suff , as we know value of Y.

So B.
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Re: 2^x+y/2^x-y=? [#permalink]
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==> If you modify the original condition and the question, from $$2^x^+^y/2^x^-^y=2^x^+^y^-^(^x^-^y^)=2^x^+^y^-^x^+^y=2^2^y$$, you only need to know y. From con 2) y=2, it is sufficient.

Therefore, the answer is B.
Answer: B
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Re: 2^x+y/2^x-y=? [#permalink]
MathRevolution wrote:
$$2^x^+^y/2^x^-^y=?$$

1) x=1
2) y=2

$$2^x^+^y/2^x^-^y=?$$ can be re-written as:

$$2^x * 2^y / 2^x * 2^{-y}$$ =?

$$2^y / 2^{-y}$$ = ?

$$2^{2y}$$ =?

We now only need to know the value of one variable i.e. $$y$$. Hence statement-2 is sufficient. Answer is B.
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Re: 2^x+y/2^x-y=? [#permalink]
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Bunuel Can you please merge the above topic.

https://gmatclub.com/forum/2-x-y-2-x-y-221942.html
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Re: 2^(x+y)/2^(x-y)=? [#permalink]
Expert Reply
NandishSS wrote:
Bunuel Can you please merge the above topic.

https://gmatclub.com/forum/2-x-y-2-x-y-221942.html

_______________
Done. Thank you.
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Re: 2^(x+y)/2^(x-y)=? [#permalink]
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Re: 2^(x+y)/2^(x-y)=? [#permalink]
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