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# Is x = 5?

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Math Expert
Joined: 02 Sep 2009
Posts: 54376

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14 Aug 2017, 06:18
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45% (medium)

Question Stats:

50% (00:49) correct 50% (01:02) wrong based on 87 sessions

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Is x = 5?

(1) $$x^2-5x=0$$

(2) $$2x^2+10x=0$$

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Joined: 20 Jun 2014
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Re: Is x = 5?  [#permalink]

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14 Aug 2017, 06:43
From A x = 0 or x = 5 not sufficient
From B x = 0 or x = -5
So sufficient B.
Math Expert
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Posts: 54376
Re: Is x = 5?  [#permalink]

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14 Aug 2017, 07:37
Bunuel wrote:
Is x = 5?

(1) $$x^2-5x=0$$

(2) $$2x^2+10x=0$$

Is x=5?

(1) $$x^2-5x=0$$ --> $$x(x-5)=0$$ --> $$x=0$$ OR $$x=5$$. Not sufficient, to answer whether $$x=5$$.

(2) $$2x^2+10x=0$$ --> $$x(x+5)=0$$ --> $$x=0$$ OR $$x=-5$$. Here we know that $$x\neq{5}$$, hence sufficient.

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Re: Is x = 5?  [#permalink]

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24 Aug 2017, 13:37
Bunuel wrote:
Is x = 5?

(1) $$x^2-5x=0$$

(2) $$2x^2+10x=0$$

We need to determine whether x = 5.

Statement One Alone:

x^2 - 5x = 0

x^2 - 5x = 0

x(x - 5) = 0

x = 0 or x = 5

Since x could be either 0 or 5, statement one is not sufficient to answer the question.

Statement Two Alone:

2x^2 + 10x = 0

2x^2 + 10x = 0

2x(x + 5) = 0

x = 0 or x = - 5

Since x could be either 0 or -5, x will never equal 5. Statement two is sufficient to answer the question.

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Re: Is x = 5?  [#permalink]

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26 Aug 2017, 03:35
B. As we know it will not be 5. Statement 1 gives 0,5 (insufficient)

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Re: Is x = 5?   [#permalink] 26 Aug 2017, 03:35
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