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What is the value of |x| ?

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Senior Manager
Joined: 29 Jan 2011
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Re: What is the value of |x| ?  [#permalink]

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24 Oct 2011, 14:03
siddhans wrote:
:(

Can someone explain whats wrong with this method ?

1) x = -|x|

this x = - (-x) or x = - (+x)

since |x| can be +ve pr -ve

thus

x = x or x = -x

x - x = 0 or x + x = 0

0=0 or 2x = 0

x =0....

|x| can't be negative. Absolute value of a number is always non-negative.

Do you follow?

Yes, I know absolute value is always positive but I am taking out absolute value and finding x
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Re: What is the value of |x| ?  [#permalink]

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24 Oct 2011, 15:41
siddhans wrote:
siddhans wrote:
:(

Can someone explain whats wrong with this method ?

1) x = -|x|

this x = - (-x) or x = - (+x)

since |x| can be +ve pr -ve

thus

x = x or x = -x

x - x = 0 or x + x = 0

0=0 or 2x = 0

x =0....

|x| can't be negative. Absolute value of a number is always non-negative.

Do you follow?

Yes, I know absolute value is always positive but I am taking out absolute value and finding x

siddhans:

when you split up stm 1 into x - x = 0 or x + x = 0
x - x = 0
x=x infinite values of x...ex 0=0, -1=-1, 2=2
and
2x=0
x=0
therefore Stm1 is insufficient
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Re: What is the value of |x| ?  [#permalink]

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24 Oct 2011, 17:58
Oh, siddhans meant x can be +ve or -ve. You wrote it was |x| can be +ve or -ve

As arzad wrote... x=x gives infinite values and x=0 gives one value, but nothing specifies which of these conditions is to be considered.
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Re: What is the value of |x| ?  [#permalink]

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14 May 2016, 06:03
siddhans wrote:
What is the value of $$|x|$$ ?
(1) $$x = -|x|$$
(2) $$x^2 = 4$$

Solution:

We need to determine the absolute value of x.

Statement One Alone:

x = -|x|

If x = -|x|, then x must be negative or 0. For example, if x = -3, -3 = -|-3|. However, since we do not have an exact value for x, statement one is not sufficient. We can eliminate answer choices A and D.

Statement Two Alone:

x^2 = 4

We can simplify by taking the square root of both sides of the equation:

√x^2 = √4

|x| = 2

Since we have 2 as the value for |x|, this answers the question.

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Re: What is the value of |x| ?  [#permalink]

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18 May 2016, 11:14
1
siddhans wrote:
What is the value of $$|x|$$ ?
(1) $$x = -|x|$$
(2) $$x^2 = 4$$

Official Guide 12 Question

 Question: 1 Page: 273 Difficulty: 600

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Video Explanations:

Its a easy question

Statement 1)
x+ lxl = 0
so from this we can conclude x is either 0 or x is negative so concrete value

Statement 2)
X^2 = 4 given
so X can be 2 or -2
but in the we are asked to find the value of lxl
and the value of lxl remains positive irrespective of value of X
so B is ans
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Re: What is the value of |x| ?  [#permalink]

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27 Jul 2017, 04:05
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Re: What is the value of |x| ?   [#permalink] 27 Jul 2017, 04:05

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