gmat prep q

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gmat prep q

by yvonne12 » Wed Mar 07, 2007 8:52 am
if xy=1 what is the value of 2^(x+y)^2 / 2^(x-y)^2

ans.16

can someone pls explain

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by sapnalakhi » Wed Mar 07, 2007 10:04 am
The above expression can be simplified as

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

= 2^4xy

= 2^4

= 16

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by yvonne12 » Wed Mar 07, 2007 11:04 am
gotcha , thanks

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by Jeff@TargetTestPrep » Sun Jun 17, 2018 7:12 pm
yvonne12 wrote:if xy=1 what is the value of 2^(x+y)^2 / 2^(x-y)^2

ans.16
Simplifying the given expression, we have:

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

2^[(x^2 + 2xy + y^2) - (x^2 -2xy + y^2)]

2^(4xy), since xy = 1, we have 2^4 = 16.

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by Brent@GMATPrepNow » Mon Jun 18, 2018 5:15 am
Here's the full question...
if XY=1 then what is the value of 2^(X+Y)²/ 2^(X-Y)²

A) 2
B) 4
C) 8
D) 16
E) 32
2^(X+Y)²/ 2^(X-Y)² = 2^(X² + 2XY + Y²)/ 2^(X² - 2XY + Y²)
= 2^(4XY) [after we subtract exponents]
= 2^4 [since XY = 1]
= 16

Answer: D

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by Brent@GMATPrepNow » Mon Jun 18, 2018 5:15 am
Brent@GMATPrepNow wrote:Here's the full question...
if XY=1 then what is the value of 2^(X+Y)²/ 2^(X-Y)²

A) 2
B) 4
C) 8
D) 16
E) 32
2^(X+Y)²/ 2^(X-Y)² = 2^(X² + 2XY + Y²)/ 2^(X² - 2XY + Y²)
= 2^(4XY) [after we subtract exponents]
= 2^4 [since XY = 1]
= 16

Answer: D

Cheers,
Brent
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by GMATGuruNY » Mon Jun 18, 2018 6:08 am
If XY=1 then what is the value of 2^(X+Y)^2/ 2^(X-Y)2^2

1)2
2) 4
3) 8
4) 16
5) 32
Let x=y=1.
Then:
2^(x+y)² / 2^(x-y)² = 2^(1+1)² / 2^(1-1)² = 2�/2� = 16/1 = 16.

The correct answer is D.
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