(2 -v5)x

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vineetbatra: Master | Next Rank: 500 Posts; Posts: 355; Joined: Thu Feb 19, 2009 12:42 pmFollowed by: 1 member; Thanked: 2 times

by vineetbatra » Thu Aug 20, 2009 1:41 pm

If (2 -v5)x = -1, then x =
A. 2 + v5
B. 1 + (v5)/2
C. 1 - (v5)/2
D. 2 - v5
E. -2 - v5

OA is A, not sure how

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Source: Beat The GMAT — Problem Solving | Thu Aug 20, 2009 1:41 pm

truplayer256: Master | Next Rank: 500 Posts; Posts: 392; Joined: Thu Jan 15, 2009 12:52 pm; Location: New Jersey; Thanked: 76 times

by truplayer256 » Thu Aug 20, 2009 2:04 pm

I'm guessing the v symbol means square root?

x=-1/2-sqrt(5)

Multiply the numerator and denominator by the conjugate of 2-sqrt(5), which is 2+sqrt(5). This will give you:

-2-sqrt(5)/-1 or 2+sqrt(5), which is option A.

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vineetbatra: Master | Next Rank: 500 Posts; Posts: 355; Joined: Thu Feb 19, 2009 12:42 pmFollowed by: 1 member; Thanked: 2 times

by vineetbatra » Thu Aug 20, 2009 2:27 pm

truplayer256 wrote:I'm guessing the v symbol means square root?

Why do you say thay V symbol means Sq Root, I thought V is another variable like X.

Can you please elaborate.

Thanks,

Vineet

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truplayer256: Master | Next Rank: 500 Posts; Posts: 392; Joined: Thu Jan 15, 2009 12:52 pm; Location: New Jersey; Thanked: 76 times

by truplayer256 » Thu Aug 20, 2009 5:40 pm

Why do you say thay V symbol means Sq Root, I thought V is another variable like X.

Can you please elaborate.

Thanks,

Vineet

Well, V must've been a square root in this case because if you had treated it as a variable and had solved for x, you would've gotten:

(2 -v5)x = -1

x=-1/2-5v

As you can clearly see, this answer doesn't match any of the answer choices given. May I know the source of this question?

Also, if you look closely, the v looks similar to the beginning of a radical sign which gave me the thought that it was a square root.

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