Not equal to Square of an integer

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swashbuckler: Newbie | Next Rank: 10 Posts; Posts: 7; Joined: Sat Sep 27, 2008 5:04 am

Not equal to Square of an integer

by swashbuckler » Sat Feb 28, 2009 2:47 pm

Hi there I'm stumped on understanding the following answer in OG 11 PS Question 56

It states that (radical sign)4 = 2 is not the square of an integer.

Is 2 squared not 4

Why is this the case? I can't seem to find a detailed explanation for the rationale behind this.

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Source: Beat The GMAT — Problem Solving | Sat Feb 28, 2009 2:47 pm

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Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 am; Location: Montreal; Thanked: 1090 times; Followed by:355 members; GMAT Score:780

by Ian Stewart » Sat Feb 28, 2009 3:06 pm

4 is the square of an integer - it's the square of 2, and also the square of -2.

2, however, is not the square of an integer. It's the square of root(2), which is roughly 1.4, and of -root(2), which is roughly -1.4.

The OG is saying that 2 is not the square of an integer.

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