## Sq. Root Problem

##### This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 18
Joined: 26 Jul 2009
Thanked: 1 times

### Sq. Root Problem

by gmatassistance » Sun Jul 26, 2009 4:05 pm
For which of the following values of x is
(sq. root of 1 - (sq. root of 2 - (sq. root of x)))
NOT defined as a real number?

A) 1
B) 2
C) 3
D) 4
E) 5[/b]

Master | Next Rank: 500 Posts
Posts: 345
Joined: 18 Mar 2009
Location: Sao Paulo-Brazil
Thanked: 12 times
GMAT Score:660
by shibal » Sun Jul 26, 2009 4:09 pm
5 because sq root of 5 is biger than 2, and when you subtract it from the sqroot of 2 it will be negtive, hence not a real number

Junior | Next Rank: 30 Posts
Posts: 15
Joined: 02 Dec 2008
Thanked: 1 times

### Is this question correctly stated

by anabbasi » Sun Jul 26, 2009 10:52 pm
Is it
(sq. root of 1 - (sq. root of 2 - (sq. root of x)))
or
(sq. root of 1 -sq.root of (sq. root of 2 - (sq. root of x)))

I think in second case D option make sense.

Junior | Next Rank: 30 Posts
Posts: 18
Joined: 26 Jul 2009
Thanked: 1 times
by gmatassistance » Mon Jul 27, 2009 3:39 pm
The correct ans. is E) 5 ...

(sq. root of 1 - (sq. root of 2 - (sq. root of x)))

D) 4 is incorrect as it leads to a REAL number unlike E) 5

Master | Next Rank: 500 Posts
Posts: 221
Joined: 21 Jan 2009
Thanked: 12 times
Followed by:1 members
by krisraam » Mon Jul 27, 2009 5:47 pm
All the choices lead to real numbers.

when x= 1==> sqrt(1) - (Sqrt(2) -Sqrt(1))
==> 2 -Sqrt(2)
Irrational number. But real number.
Similarly for all other choices.

If the number is not a real number it need to be either imaginary number or complex number.

Thanks
Raama

Newbie | Next Rank: 10 Posts
Posts: 3
Joined: 19 May 2009
Thanked: 1 times
by b2eby » Mon Jul 27, 2009 6:19 pm
All numbers on the GMAT are real numbers. What's the source?

Junior | Next Rank: 30 Posts
Posts: 18
Joined: 26 Jul 2009
Thanked: 1 times
by gmatassistance » Tue Jul 28, 2009 4:30 pm
The problem is from one of the GMAT Prep exams ... per the earlier explanation the answer is 5 because it leads to a square root of a negative which isn't a real number.

• Page 1 of 1