Is y an integer ?

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sands_of_time: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Tue Apr 07, 2009 4:47 am

by sands_of_time » Mon Apr 13, 2009 9:19 pm

If x^2 + 5y=49, is y an integer ?

a) 1<x<4
b) x^2 is an integer

Please help me in solving this question.

OA E

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Source: Beat The GMAT — Data Sufficiency | Mon Apr 13, 2009 9:19 pm

cramya: Legendary Member; Posts: 2467; Joined: Thu Aug 28, 2008 6:14 pmFollowed by: 11 members; Thanked: 331 times

by cramya » Mon Apr 13, 2009 10:24 pm

b) x^2 is an integer

x^2= 4 y=9 the condition would be true

x^2=2 y= 47/5 the condition would be true

INSUFF

Stmt I

1<x<4

x=2 and x^2= 4 y=9 the condition would be true

x=sqrt(2) and x^2=2 y= 47/5 the condition would be true

INSUFF

TOGETHER:

same examples above

INSUFF

E

Takeaway:x^2 is an integer does not mean x is an integer unless it is explicitly stated in the problem

P.S. Useful to know

SQRT(2) = 1.414
SQRT(3) = 1.732
SQRT(5) = 2.23

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sands_of_time: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Tue Apr 07, 2009 4:47 am

by sands_of_time » Mon Apr 13, 2009 10:35 pm

Thanks Cramya!! That cleared my doubt.

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