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What s the value of x ? (there is no extra condition or

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laxieqv
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What s the value of x ? (there is no extra condition or [#permalink] New post   12 Mar 2006, 11:07
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What’s the value of x ? (there is no extra condition or description for x)

(I) sqrt[(x – 5)(x + 4)] > 10

(II) sqrt[(x – 5)(x + 4)] < 11



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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   12 Mar 2006, 12:11
(x – 5)(x + 4) > 100
(x – 5)(x + 4) < 121


E.
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chuckle
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   12 Mar 2006, 15:04
Me too for E.
From question statement, x >= 5.
From statement 1, x belongs to [5,infinity].
From statement 2, x belongs to [5,approximately 5.5].
Since there are infinite real numbers between 5 and 5.5, answer is E.
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laxieqv
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   13 Mar 2006, 06:47
good job everyone, OA is E! :)
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lhotseface
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   13 Mar 2006, 11:27
Can't factorize I or II...looks like no roots for either. Can check the delta values but 2 minutes are up...E for me.

laxieqv wrote:
What’s the value of x ? (there is no extra condition or description for x)

(I) sqrt[(x – 5)(x + 4)] > 10

(II) sqrt[(x – 5)(x + 4)] < 11
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old_dream_1976
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   03 Apr 2006, 19:15
laxieqv wrote:
What’s the value of x ? (there is no extra condition or description for x)

(I) sqrt[(x – 5)(x + 4)] > 10

(II) sqrt[(x – 5)(x + 4)] < 11


Laxie,

Can you please explain this? Why not C ?

Thank you
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laxieqv
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   04 Apr 2006, 04:41
old_dream_1976 wrote:
laxieqv wrote:
What’s the value of x ? (there is no extra condition or description for x)

(I) sqrt[(x – 5)(x + 4)] > 10

(II) sqrt[(x – 5)(x + 4)] < 11


Laxie,

Can you please explain this? Why not C ?

Thank you


For each inequality, both sides are non-negative so we can square them and get:
100< (x-5)(x+4) < 121 -->100 < x^2- x -20 <121 --> 120<x^2-x<141
There're many values of x satisfying this ( remember x is not necessarily integer)
That's why it's E.
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   04 Apr 2006, 04:51
1)

(x-5)(x+4) > 100
x^2 - x - 120 > 0

1/2 +/- 1/2(sqrt(81)) > 0
Gives a range of x

2) (x-5)(x+4) < 11
x^2 - x - 31 < 0
1/2 +/- 1/2(sqrt(125)) < 0

Gives a range of x

Using both, on the number line, there will still be a range of values for x.

Insufficient.

Ans E
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trivikram
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   04 Apr 2006, 15:39
Both are independently not sufficient

Combine both

Let y =sqrt[(x – 5)(x + 4) ]

from(i) and (ii)

10<y<11

Since amny values exist it is E
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positive soul
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   05 Apr 2006, 10:15
I got E as well. There are many possible values for X.
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old_dream_1976
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   10 Apr 2006, 20:00
laxieqv wrote:
old_dream_1976 wrote:
laxieqv wrote:
What’s the value of x ? (there is no extra condition or description for x)

(I) sqrt[(x – 5)(x + 4)] > 10

(II) sqrt[(x – 5)(x + 4)] < 11


Laxie,

Can you please explain this? Why not C ?

Thank you


For each inequality, both sides are non-negative so we can square them and get:
100< (x-5)(x+4) < 121 -->100 < x^2- x -20 <121 --> 120<x^2-x<141
There're many values of x satisfying this ( remember x is not necessarily integer)
That's why it's E.


I thought I thanked you for the Explaination. but I did not.

So here it is. I really appreciate you and others who take time to try to explain things.
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sm176811
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   10 Apr 2006, 23:56
Yeah could not factorize... irregular roots!

So E I guess!
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vivek123
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Re: What s the value of x ? (there is no extra condition or [#permalink] New post   11 Apr 2006, 04:07
Hey Laxie, you are a CEO now :-D I'm bit late to wish you!

Congratulations! :beer



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This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
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Re: What s the value of x ? (there is no extra condition or [#permalink]
11 Apr 2006, 04:07
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