Looks simple. OA not matching.

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Looks simple. OA not matching.

by anandr84 » Fri Oct 30, 2009 7:25 pm
Is x^2 + y^2 > 6?
(1) (x + y)^2 > 6
(2) xy = 2

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

OA is E acc me it should be C
Source: — Data Sufficiency |

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by scoobydooby » Fri Oct 30, 2009 8:10 pm
when you combine the two,

x^2+y^2+4>6
=> x^2+y^2>2
we cant conclude the above is greater than 6. it can be less than 6 or greater than 6. there are numbers greater than 2 but less than 6.
hence, E

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by life is a test » Sat Oct 31, 2009 7:06 am
I am not sure if I am evaluating this correctly but would appreciate if someone could point out any problems with my approach. thanks!

1. expand out to give x^2 + y^2 = 6-2xy
--> putting this back into the original stem give 6-2xy>6 -> -2xy>0 --> insuff

2. try x=2, y=1 which results in ans no. try out x=4, y=1/2 which results in ans yes hence insuff

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by anandr84 » Sat Oct 31, 2009 7:41 am
Thanx guys :)