gmatprep - number line

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gmatprep - number line

by Gurpinder » Mon Sep 20, 2010 6:52 am
Image


are the first three NOT finite in length?
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by beatthegmatinsept » Mon Sep 20, 2010 7:26 am
Gurpinder wrote:Image


are the first three NOT finite in length?
I don't see an image :(
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by apex231 » Mon Sep 20, 2010 7:32 am
Option E seems correct.

the question asks for finite length segment, this eliminates options A, B and C.

another condition asked in question is "single" line segment. This eliminates option D.

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by Gurpinder » Mon Sep 20, 2010 7:32 am
beatthegmatinsept wrote:
Gurpinder wrote:Image


are the first three NOT finite in length?
I don't see an image :(
Hm.....

go here: https://postimage.org/image/1lbr0xb7o/
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by Gurpinder » Mon Sep 20, 2010 7:33 am
apex231 wrote:Option E seems correct.

the question asks for finite length segment, this eliminates options A, B and C.

another condition asked in question is "single" line segment. This eliminates option D.
Thought so.

Thx apex!
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by Brian@VeritasPrep » Mon Sep 20, 2010 2:28 pm
Hey Gurpinder,

This may have already been answered, but the wording "which s finite" means that anything that is infinite is incorrect.

Let's just consider something quick like x>0. Well, any positive number would satisfy that, and you can always add 1 to the biggest number you can think of (and then do it again, and again, and again), so there are an infinite number of numbers that would satisfy that, and the line would go infinitely to the right.

With something like x^2 > 4, that means that anything other than values between -2 and 2 would satisfy this inequality. 25, for example, when squared becomes much larger (625) than 4, and you can keep increasing x to get bigger and bigger. That segment would go on infinitely to the right; the same is true of a line extending all the way to the left. -100, when squared, is much bigger than 4, too, and you can keep making that value lower and lower by adding negative numbers, so it would also have a line extend all the way left, infinitely.

What they're looking for is an inequality that will pin the values of x between two. Something like x^2 < 4 would work. The only numbers that work are values of x that have an absolute value of less than 2. -1 works, 1 works, 0 works...but -3 and 3 do not, so that line would be a line of finite length between -2 and 2.
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by Gurpinder » Mon Sep 20, 2010 2:32 pm
Brian@VeritasPrep wrote:Hey Gurpinder,

This may have already been answered, but the wording "which s finite" means that anything that is infinite is incorrect.

Let's just consider something quick like x>0. Well, any positive number would satisfy that, and you can always add 1 to the biggest number you can think of (and then do it again, and again, and again), so there are an infinite number of numbers that would satisfy that, and the line would go infinitely to the right.

With something like x^2 > 4, that means that anything other than values between -2 and 2 would satisfy this inequality. 25, for example, when squared becomes much larger (625) than 4, and you can keep increasing x to get bigger and bigger. That segment would go on infinitely to the right; the same is true of a line extending all the way to the left. -100, when squared, is much bigger than 4, too, and you can keep making that value lower and lower by adding negative numbers, so it would also have a line extend all the way left, infinitely.

What they're looking for is an inequality that will pin the values of x between two. Something like x^2 < 4 would work. The only numbers that work are values of x that have an absolute value of less than 2. -1 works, 1 works, 0 works...but -3 and 3 do not, so that line would be a line of finite length between -2 and 2.
Thx alot for that Brian.

Great explanation!!!!
"Do not confuse motion and progress. A rocking horse keeps moving but does not make any progress."
- Alfred A. Montapert, Philosopher.