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Is x^2*y^4 divisible by 9? 1. x is an integer divisible by 3

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Is x^2*y^4 divisible by 9? 1. x is an integer divisible by 3 [#permalink]  11 Dec 2007, 05:33
Is x^2*y^4 divisible by 9?

1. x is an integer divisible by 3
2. xy is an integer divisible by 9
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Re: x^2*y^4 divisible by 9? [#permalink]  11 Dec 2007, 05:42
bmwhype2 wrote:
Is x^2*y^4 divisible by 9?

1. x is an integer divisible by 3
2. xy is an integer divisible by 9

I get D.

Stmt 1 says x is a multiple of 3. Any multiple of 3 squared will be divisible by 9. Suff

Stmt 2 says xy is a multiple of 9. Therefore either x or y is a multiple of 9 or x and y are both a multiple of 3. In all cases when you will get a number that is divisible by 9. Suff
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Re: x^2*y^4 divisible by 9? [#permalink]  11 Dec 2007, 10:44
gixxer1000 wrote:
bmwhype2 wrote:
Is x^2*y^4 divisible by 9?

1. x is an integer divisible by 3
2. xy is an integer divisible by 9

I get D.

Stmt 1 says x is a multiple of 3. Any multiple of 3 squared will be divisible by 9. Suff

Stmt 2 says xy is a multiple of 9. Therefore either x or y is a multiple of 9 or x and y are both a multiple of 3. In all cases when you will get a number that is divisible by 9. Suff

if y is 1/9, then the multiple of 3 squared be affected. 3* 1/9 = 1/3

1/3 is not divisible by 9
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Re: x^2*y^4 divisible by 9? [#permalink]  13 Dec 2007, 11:49
bmwhype2 wrote:
Is x^2*y^4 divisible by 9?

1. x is an integer divisible by 3
2. xy is an integer divisible by 9

I'd say E

(1) we don't know if y is an integer, so INSUFF
(2) again, we don't whether x and y are integers (consider x=2 and y=4.5). INSUFF

(1)+(2). By the same token, it could be that x=3 and y=3 (the answer is YES), or x=6 and y=3/2 (the answer is NO). INSUFF
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Re: x^2*y^4 divisible by 9? [#permalink]  13 Dec 2007, 15:40
bmwhype2 wrote:
Is x^2*y^4 divisible by 9?

1. x is an integer divisible by 3
2. xy is an integer divisible by 9

I get A.

obs x/3= integer so x^2/3^2 is an integer.

2: can think of many that the answer is yes. what if y=1/9 and x=9

we have 81*1/9=9. divisible by 9.

now 81^2*1/9^4 --> 1. Which is not divisible by 9.

Insuff.
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Okay, I can see why the answer is E.

"Divisible by 9" means that the result should be an integer.
In I. and II. y could be integer or not, so if y is a fraction, we will always left with the fraction, that's why the answer is E.
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Re: x^2*y^4 divisible by 9? [#permalink]  13 Dec 2007, 22:57
GMATBLACKBELT wrote:
bmwhype2 wrote:
Is x^2*y^4 divisible by 9?

1. x is an integer divisible by 3
2. xy is an integer divisible by 9

I get A.

obs x/3= integer so x^2/3^2 is an integer.

2: can think of many that the answer is yes. what if y=1/9 and x=9

we have 81*1/9=9. divisible by 9.

now 81^2*1/9^4 --> 1. Which is not divisible by 9.

Insuff.

arghhh didnt apply the logic from 2 to 1 -_-
Re: x^2*y^4 divisible by 9?   [#permalink] 13 Dec 2007, 22:57
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