If x2 is a positive integer, is x a positive integer?
(1)Sqrt x^2 is an integer.
(2)Sqrt x^2 = x
Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
EITHER statement BY ITSELF is sufficient to answer the question.
Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, requiring more data pertaining to the problem.
DS number properties
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- ani781
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IMO answer is: B
Reason :
From(1)=> Sqrt x^2 is an integer.
Let x^2 = 16; then sqrt 16 = +4 or -4; ... so not sufficient.
From(2)=> sqrt x^2 = x; So clearly with the example taken from (1) the answer narrows down to only +4. Sufficient.
Reason :
From(1)=> Sqrt x^2 is an integer.
Let x^2 = 16; then sqrt 16 = +4 or -4; ... so not sufficient.
From(2)=> sqrt x^2 = x; So clearly with the example taken from (1) the answer narrows down to only +4. Sufficient.
- sanju09
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I. When x = -2, √4 is 2 an integer, but x is not positive, hence NO. But, when x = 2, √4 is 2 an integer, and x is positive, hence YES. Insufficient. Get rid of A, D.imskpwr wrote:If x2 is a positive integer, is x a positive integer?
(1)Sqrt x^2 is an integer.
(2)Sqrt x^2 = x
Statement (1) BY ITSELF is sufficient to answer the question, but statement (2) by itself is not.
Statement (2) BY ITSELF is sufficient to answer the question, but statement (1) by itself is not.
Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, even though NEITHER statement BY ITSELF is sufficient.
EITHER statement BY ITSELF is sufficient to answer the question.
Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question, requiring more data pertaining to the problem.
II. Square root of a positive number is always a positive number. Hence, if x^2 is a positive integer and √x^2 = x, x is definitely a positive integer. [spoiler]Sufficient
Choose B[/spoiler]
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Sanjeev K Saxena
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Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
- ani781
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Hi Sanju, I get it now , what was wrong with my understanding. Sqrt 16 can't be +4 or -4... it is only +4.I. When x = -2, √4 is 2 an integer, but x is not positive, hence NO. But, when x = 2, √4 is 2 an integer, and x is positive, hence YES. Insufficient. Get rid of A, D.
Thanks a lot for this.