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DS: Number prop question. Is √(x + y) an integer?

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DS: Number prop question. Is √(x + y) an integer?

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Is √(x + y) an integer?
(1) x3 = 64
(2) x2 = y - 3

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(1) x^3 = 64

x = 4 -- No info about 'y' - Insufficient

(2) x^2 = y - 3 -- 2 unknowns, cannot deduce enough about 'x' and 'y'.

Together, x=4, therefore y = 19 and √23 is not an integer. C IMO

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dvinoth86 wrote:
Is √(x + y) an integer?
(1) x3 = 64
(2) x2 = y - 3
(1) x^3 = 64 does not give any info about y; NOT sufficient.

(2) x² = y - 3
If x = 1, y = 4, then √5 is not an integer.
If x = 2, y = 7, then √(x + y) = 3 is an integer.
No definite answer; NOT sufficient.

Combining (1) and (2), we know x = 4, so y = 19, which implies √23 is not an integer; SUFFICIENT.

The correct answer is C.

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I believe B should be sufficient to give us the answer. Because give that x^2 = y-3, so we can imply that y =x^2+3 , and put that in equation. Now we need to answer if Sq root(X^2 + X +3) would be Integer or not and this value is never integer. Therefore, B is sufficient answer.
Please comment if you agree to this

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amitasricky@gmail.com wrote:
I believe B should be sufficient to give us the answer. Because give that x^2 = y-3, so we can imply that y =x^2+3 , and put that in equation. Now we need to answer if Sq root(X^2 + X +3) would be Integer or not and this value is never integer. Therefore, B is sufficient answer.
Please comment if you agree to this
The square root of (X^2 + X +3) is an integer when x=2, but it is not an integer when x=1
So, statement 2 cannot be sufficient.

Cheers,
Brent

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amitasricky@gmail.com wrote:
I believe B should be sufficient to give us the answer. Because give that x^2 = y-3, so we can imply that y =x^2+3 , and put that in equation. Now we need to answer if Sq root(X^2 + X +3) would be Integer or not and this value is never integer. Therefore, B is sufficient answer.
Please comment if you agree to this
I think you are assuming that X^2 + X +3 = 0 but it does not have to be equal to 0.

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