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singh_amit19
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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 24 Sep 2007, 13:20
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If x2 + y2 =1, is x + y =1?
(1) xy =o
(2) y = 0

(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

-------------------------------------------------------------------------
This a easy one....i picked A

X^2+Y^2+2XY = 1 + 2XY = 1 (if (1) info is given)
X=+/- 1 if (2) given

so A

Please post any other views????



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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 24 Sep 2007, 13:38
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singh_amit19
If x2 + y2 =1, is x + y =1?
(1) xy =o
(2) y = 0

(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

-------------------------------------------------------------------------
This a easy one....i picked A

X^2+Y^2+2XY = 1 + 2XY = 1 (if (1) info is given)
X=+/- 1 if (2) given

so A

Please post any other views????
Show more


Stmnt1
Here it means either x or y is 0 . So that would end up as either
x = (+/-) 1 or y = (+/-) 1 . Dont get anything from here. A insuff.

Stmnt2
x = +/- 1 . So B is insuff too. Its just like stmnt 1 .

Combining , I dont think still we can prove x+y = 1 .
I would give E.
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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 24 Sep 2007, 14:30
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singh_amit19
If x2 + y2 =1, is x + y =1?
(1) xy =o
(2) y = 0

(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

-------------------------------------------------------------------------
This a easy one....i picked A

X^2+Y^2+2XY = 1 + 2XY = 1 (if (1) info is given)
X=+/- 1 if (2) given

so A

Please post any other views????
Show more


agreed with E.

from stmt 1, we know that either x or y is 0 but the other value is 1 or -1, so x + y may or may not be 1
INSUFFICIENT

from stmt 2, we know that y is 0, but again x can be 1 or -1

putting them together doesn't yield any more information so both are not sufficient

by the way, BE CAREFUL x^2 + y^2 DOES NOT equal to (x+y)^2 as you noted above.. test out some values and you'll know what i mean
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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 24 Sep 2007, 20:34
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x^2 + y^2 = 1

st1:
xy = 0
So either x is 0, or y is 0.

If x is 0, y^2 = 1, y is either 1 or -1. x+y could be 1 or -1.
If y is 0, x^2 = 1, x is either 1 or -1. x+y could be 1 or -1.
Insufficient.

St2:
y is 0, so x is either 1 or -1. x+y could be 1 or -1.
Insufficient.

St1 & St2:
x is still either 1 or -1. x+y could be 1 or -1.
Insufficient.

Ans E
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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 24 Sep 2007, 21:22
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ashkrs
singh_amit19
If x2 + y2 =1, is x + y =1?
(1) xy =o
(2) y = 0

(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

-------------------------------------------------------------------------
This a easy one....i picked A

X^2+Y^2+2XY = 1 + 2XY = 1 (if (1) info is given)
X=+/- 1 if (2) given

so A

Please post any other views????

Stmnt1
Here it means either x or y is 0 . So that would end up as either
x = (+/-) 1 or y = (+/-) 1 . Dont get anything from here. A insuff.

Stmnt2
x = +/- 1 . So B is insuff too. Its just like stmnt 1 .

Combining , I dont think still we can prove x+y = 1 .
I would give E.
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E .. That was good one.. A common trap for these types of questions..
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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 25 Sep 2007, 13:08
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I thought ans is A??

x^2 + y^2 = 1
(x+y)^2 - 2xy = 1
x+y = 1
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GMATBLACKBELT
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If x2 + y2 =1, is x + y =1? (1) xy =o (2) y = 0 (A)Statement 25 Sep 2007, 20:23
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singh_amit19
If x2 + y2 =1, is x + y =1?
(1) xy =o
(2) y = 0

(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

-------------------------------------------------------------------------
This a easy one....i picked A

X^2+Y^2+2XY = 1 + 2XY = 1 (if (1) info is given)
X=+/- 1 if (2) given

so A

Please post any other views????
Show more


I say E.

for x^2+y^2=1. Then x or y has to be 0. now is x+y=1?

Starting w/ S2 b/c its easier.

S2:
y=0. 1^2+0=1 -1^2+0=1. so 1+0=1, but -1+0 dsnt =1... insuff.


S1:
xy=0 well -1*0=0 or 1*0=0. Same logic as in S1 when apply to the problem. Insuff.

1 and 2: again values could be 1,0 or -1,0 or vice versa.


Insuff.



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Data Sufficiency (DS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
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