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# if x<0 then sqrt(-x|x|) is 1. -x 2. -1 3. 1 4. x 5.

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Manager
Joined: 04 Jan 2006
Posts: 51
Followers: 1

Kudos [?]: 0 [0], given: 0

if x<0 then sqrt(-x|x|) is 1. -x 2. -1 3. 1 4. x 5. [#permalink]  27 Jan 2006, 22:50
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if x<0 then sqrt(-x|x|) is
1. -x
2. -1
3. 1
4. x
5. sqrt(x)
VP
Joined: 21 Sep 2003
Posts: 1069
Location: USA
Followers: 3

Kudos [?]: 38 [0], given: 0

A?

since x<0 => |x| = -x

sqrt (-x|x|) = sqrt (-x*-x) = sqrt(x^2) = +/-x

But since x < 0, we need to pick the negative root of x.

Hence (I think) it is -x.
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- Bernard Edmonds

Senior Manager
Joined: 13 Jun 2005
Posts: 253
Location: Haverhill, MA
Followers: 1

Kudos [?]: 5 [0], given: 0

good question and good explanation.

Thanks.
Manager
Joined: 30 Jan 2005
Posts: 143
Followers: 1

Kudos [?]: 1 [0], given: 0

giddi77 wrote:
A?

since x<0 => |x| = -x

sqrt (-x|x|) = sqrt (-x*-x) = sqrt(x^2) = +/-x

But since x < 0, we need to pick the negative root of x.

Hence (I think) it is -x.

Hi giddi

does this solution make sense ????

x < 0 ....... |-x| = x
sqrt (-x * |-x|)
sqrt (-x * x)
sqrt( -x^2)
sqrt & ^2 gets cancelled
u are left with -x as the answer !!
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"Nothing is Impossible"

Senior Manager
Joined: 11 Nov 2005
Posts: 332
Location: London
Followers: 1

Kudos [?]: 8 [0], given: 0

I think it is C. 1

take any value for x and put it in the equation.

if x is -4, sqrt[ - (-4)/|-4|]
= sqrt(+4/4)
=sqrt 1= 1.

if x<0 then sqrt(-x|x|) is
1. -x
2. -1
3. 1
4. x
5. sqrt(x)
Senior Manager
Joined: 13 Jun 2005
Posts: 253
Location: Haverhill, MA
Followers: 1

Kudos [?]: 5 [0], given: 0

sunshine the question is
sqrt(-x*|x|) and not sqrt(-x/|x|)
Senior Manager
Joined: 11 Nov 2005
Posts: 332
Location: London
Followers: 1

Kudos [?]: 8 [0], given: 0

In that case it should be A. -X.

Same logic
take any value for x and put it in the equation.

if x is -4, sqrt[ - (-4)*|-4|]
= sqrt(+4*4) = 4, that is -x

--------------------------------------------
Sorry I overlooked the question

sperumba wrote:
sunshine the question is
sqrt(-x*|x|) and not sqrt(-x/|x|)
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