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absolute value

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absolute value

by angela22 » Fri Apr 04, 2008 4:12 pm
If x<0, then the square root of -x|x| is...

a) -x

b) -1

c) 1

d) x

e) square root of x


i'm probably missing something cause i thought it was d. the answer is a but i don't know how they got the negative. please help! thank you!
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by tmmyc » Fri Apr 04, 2008 5:43 pm
-x*lxl where x<0

Pick a number: x=-2

-x*lxl
-(-2)*l-2l
2*l-2l
2*2
4

sqrt(4) = 2
which is our above value of x multiplied by -1; hence the answer is -x.
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by angela22 » Fri Apr 04, 2008 6:49 pm
thank you!!
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by maihuna » Mon Apr 13, 2009 9:59 am
I cannt understand this, can somebody elaborate please..
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by DeepakR » Mon Apr 13, 2009 6:51 pm
Given x<0 and we need to find square root of -x|x|..
so -(-x)|-x| = -(-x)*x=x^2. Now square root (x^2)=+x or -x. But since x<0 it will be -x

- Deepak
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