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# If (x^2)/9 - 4/(y^2) = 12, what is the value of x? (1) x/3 +

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Manager
Joined: 11 Apr 2008
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Location: Chicago
If (x^2)/9 - 4/(y^2) = 12, what is the value of x? (1) x/3 + [#permalink]

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05 Aug 2008, 14:02
If (x^2)/9 - 4/(y^2) = 12, what is the value of x?
(1) x/3 + 2/y = 6
(2) x/3 - 2/y = 2

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Factorials were someone's attempt to make math look exciting!!!

Last edited by brokerbevo on 06 Aug 2008, 07:06, edited 1 time in total.
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05 Aug 2008, 14:07
I think it's D

The first one we should be able to solve for y in terms of x and substitute that into the equatino given in the stem.

The second, x = 12 and y = 1. I think it's sufficient. But, just because I came up with AN answer, doesn't mean it's the ONLY answer which would make it insufficient.

brokerbevo wrote:
If (x^2)/9 - 4/(y^2) = 12, what is the value of x?
(1) x/3 + 2/y = 16
(2) x/3 - 2/y = 2

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Senior Manager
Joined: 31 Jul 2008
Posts: 280

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05 Aug 2008, 14:13
In my opinion the answer should be E

as the equation in the question breaks to :

(x/3 + 2/y)(x/3-2/y)=12

Each alone is insufficient

and if we combine both it gives a false result (16*2=32)
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Joined: 17 Jun 2008
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05 Aug 2008, 17:15
brokerbevo wrote:
If (x^2)/9 - 4/(y^2) = 12, what is the value of x?
(1) x/3 + 2/y = 16
(2) x/3 - 2/y = 2

(x/3 + 2/y )(x/3 - 2/y )=12

hence (1) and (2) both help solving this independently

IMO D
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Manager
Joined: 04 Sep 2007
Posts: 207

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05 Aug 2008, 19:13
Another one for D and I agree with solutions posted by the previous posters. Either one of the two choices is sufficient to answer the question.
Manager
Joined: 23 Apr 2008
Posts: 83

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06 Aug 2008, 02:45

IF WE SOLVE THE TWO EQUATIONS FOR X ..V GET THE VALUES FOR EACH VARIABLE(X&Y)

WHAT IS THE OA?
Director
Joined: 27 May 2008
Posts: 539

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06 Aug 2008, 03:10
brokerbevo wrote:
If (x^2)/9 - 4/(y^2) = 12, what is the value of x?
(1) x/3 + 2/y = 16
(2) x/3 - 2/y = 2

i think there is a typo in the question.. either the question stem should be (x^2)/9 - 4/(y^2) = 32
or statemen 1 should be x/3 + 2/y = 6

and the answer would be D

if there is no typo then both statements are conflicting each other.. not possible with a GMAT question .. source please.
Senior Manager
Joined: 16 Jul 2008
Posts: 285

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06 Aug 2008, 04:11
durgesh79 wrote:
brokerbevo wrote:
If (x^2)/9 - 4/(y^2) = 12, what is the value of x?
(1) x/3 + 2/y = 16
(2) x/3 - 2/y = 2

i think there is a typo in the question.. either the question stem should be (x^2)/9 - 4/(y^2) = 32
or statemen 1 should be x/3 + 2/y = 6

and the answer would be D

if there is no typo then both statements are conflicting each other.. not possible with a GMAT question .. source please.

I think you are right and the first statement ends with =6. It's from MGMAT, and IIRC the OA is D.
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Senior Manager
Joined: 06 Apr 2008
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06 Aug 2008, 05:02
brokerbevo wrote:
If (x^2)/9 - 4/(y^2) = 12, what is the value of x?
(1) x/3 + 2/y = 16
(2) x/3 - 2/y = 2

D)

Both 1) and 2) leads to eqn as given in 1 and 2
Manager
Joined: 11 Apr 2008
Posts: 128
Location: Chicago

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06 Aug 2008, 07:03
Sorry. I totally abandoned this thread. Yes, statement 1 should be = 6. I must have typed it in wrong. Sorry for the confusion.

Could someone please provide an explanation given the fixed error?
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Factorials were someone's attempt to make math look exciting!!!

Director
Joined: 27 May 2008
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06 Aug 2008, 07:14
1
KUDOS
brokerbevo wrote:
Sorry. I totally abandoned this thread. Yes, statement 1 should be = 6. I must have typed it in wrong. Sorry for the confusion.

Could someone please provide an explanation given the fixed error?

x/3 = a
2/y = b

Q: a^2 - b^2 = 12
(a+b)(a-b) = 12 --------(1)

statement 1 : a+b=6, we can find a-b from (1) and then we can find a and b ... suff
statement 2 : a-b=2, we can find a+b from (1) and then we can find a and b .. suff

Option D
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06 Aug 2008, 09:18
durgesh79 wrote:
brokerbevo wrote:
Sorry. I totally abandoned this thread. Yes, statement 1 should be = 6. I must have typed it in wrong. Sorry for the confusion.

Could someone please provide an explanation given the fixed error?

x/3 = a
2/y = b

Q: a^2 - b^2 = 12
(a+b)(a-b) = 12 --------(1)

statement 1 : a+b=6, we can find a-b from (1) and then we can find a and b ... suff
statement 2 : a-b=2, we can find a+b from (1) and then we can find a and b .. suff

Option D

So we can conclude that

State 1 & State 2 = Question
-- then Answer is D ( each statent is linear equation with two common unknown variables)

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Manager
Joined: 11 Apr 2008
Posts: 128
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06 Aug 2008, 13:27
durgesh79 wrote:
brokerbevo wrote:
Sorry. I totally abandoned this thread. Yes, statement 1 should be = 6. I must have typed it in wrong. Sorry for the confusion.

Could someone please provide an explanation given the fixed error?

x/3 = a
2/y = b

Q: a^2 - b^2 = 12
(a+b)(a-b) = 12 --------(1)

statement 1 : a+b=6, we can find a-b from (1) and then we can find a and b ... suff
statement 2 : a-b=2, we can find a+b from (1) and then we can find a and b .. suff

Option D

Nice, I like how you substituted the expressions with variables in order to simplify the math. I've never heard of that approach before---I added it to my personal strategy guide.
+1 for you

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Factorials were someone's attempt to make math look exciting!!!

Re: exponential equation mess   [#permalink] 06 Aug 2008, 13:27
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# If (x^2)/9 - 4/(y^2) = 12, what is the value of x? (1) x/3 +

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