What is value of x? : GMAT Data Sufficiency (DS)
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# What is value of x?

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What is value of x? [#permalink]

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29 Jun 2012, 08:00
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Question Stats:

64% (01:54) correct 36% (00:53) wrong based on 150 sessions

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What is value of x?

(1) 4x^2-4x+1=0

(2) 4x^2-1=0
[Reveal] Spoiler: OA

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Re: What is value of x? [#permalink]

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29 Jun 2012, 08:04
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What is value of x?

(1) 4x^2-4x+1=0 --> $$(2x-1)^2=0$$ --> $$2x-1=0$$ --> $$x=\frac{1}{2}$$. Sufficient.

(2) 4x^2-1=0 --> $$x^2=\frac{1}{4}$$ --> $$x=-\frac{1}{2}$$ or $$x=\frac{1}{2}$$. Not sufficient.

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Re: What is value of x? [#permalink]

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29 Jun 2012, 08:15
Thanks alot bunuel .....

4x^2-4x+1=0 to (2x-1)^2 ...?? how did u simplify it?
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Re: What is value of x? [#permalink]

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29 Jun 2012, 10:00
sanjoo wrote:
Thanks alot bunuel .....

4x^2-4x+1=0 to (2x-1)^2 ...?? how did u simplify it?

$$(a-b)^2=a^2-2ab+b^2$$;
$$(2x-1)^2=(2x)^2-2*2x+1^2=4x^2-4x+1$$.

Hope it's clear.
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Re: What is value of x? [#permalink]

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30 Jun 2012, 07:58
Hai Bunnel

can you tell me how to find that statement 1 is in (a-b)^2 farm. Is there any method behind this. Plz explain
Re: What is value of x?   [#permalink] 30 Jun 2012, 07:58
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