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Can anyone please help me out with this DS question?

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Source: — Data Sufficiency |
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by eaakbari » Fri Nov 30, 2012 12:49 am
You have made a typographical error and I am not sure what the OA is
but my answer is D

Stem : We need xy(x+y)
xy = -6 , also implies x & y are non-zero
We need to find x + y
Since we know xy=-6, finding either x or y will suffice

(I) x-y = 5
Multiplying both sides by y (since y is non-zero)

xy - y^2 = 5y

But xy = -6

-6 - y^2 = 5y
Its a quad equation which can be solved. Hence Suff.

(II) x*y^2 = 18

Since xy=-6
-6*y = 18
Hence y = -3

Hence Suff


IMO D
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by aman88 » Fri Nov 30, 2012 1:15 am
I am sorry about the typographical error.

I meant, my answer is also D but the QA is B.
That's why I got confused.

Thanks.
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by eaakbari » Fri Nov 30, 2012 1:33 am
Yes, sorry the answer is B.

That's becuase in Case I.

The quadratic equation -6 - y^2 = 5y OR

y^2 +5y + 6
simplifies to

(y+2)(y-3)

Since y can assume both values -2 or -3
It is not sufficient.

Hence B

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by aman88 » Fri Nov 30, 2012 3:47 am
Yes for sure. Thanks a lot. I appreciate that. :)

-Aman
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