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Kaplan question - stuck!

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Kaplan question - stuck!

by vanesslondon » Fri Jan 25, 2008 11:30 am
Hey guys hope you can help with the following question from Kaplan's Math book. I'm just starting out and would appreciate guidance! Thank you!

'solve the following inequality for x'

6>x+4>4

I can post the answer if people want to know!
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by sankruth » Fri Jan 25, 2008 11:42 am
Is the answer 0 < x < 2?
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by vanesslondon » Fri Jan 25, 2008 11:50 am
yes! well done! would you mind explaining? Many thanks!
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Re: Kaplan question - stuck!

by Stuart@KaplanGMAT » Fri Jan 25, 2008 12:21 pm
vanesslondon wrote:'solve the following inequality for x'

6>x+4>4

With one big exception, we manipulate inequalities just like equations. It doesn't matter how many different pieces there are to the inequality.

Here, we want to solve for x.

Right now, we have x + 4... so, to get x by itself, we subtract 4 from all 3 parts of the inequality to get:

6 - 4 > x + 4 - 4 > 4 - 4

or

2 > x > 0

all done!
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by vanesslondon » Fri Jan 25, 2008 12:25 pm
Thanks, Stuart, I so appreciate it! This was driving me mad!
I kept trying to get the answer by subtracting 4 from just one of the sides.
I am SO relieved - you know when a question won't let you go? Thank you!
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by vanesslondon » Fri Jan 25, 2008 12:31 pm
Sorry - one last thing:

do we still do the same thing to all parts of the equation, even if that entity isn't present in one part? By which I mean, if we have

2x>x>4

if we minus x, do we get

x>4-x

?

I just made up that question - completely hypothetical! Thank you!
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by vanesslondon » Fri Jan 25, 2008 12:34 pm
Sorry - one last thing:

do we still do the same thing to all parts of the equation, even if that entity isn't present in one part? By which I mean, if we have

2x>x>4

if we minus x, do we get

x>4-x

?

I just made up that question - completely hypothetical! Thank you!
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by Stuart@KaplanGMAT » Fri Jan 25, 2008 1:25 pm
vanesslondon wrote:Sorry - one last thing:

do we still do the same thing to all parts of the equation, even if that entity isn't present in one part? By which I mean, if we have

2x>x>4

if we minus x, do we get

x>4-x
2x > x > 4

if we subtract x from all 3 parts we get

2x - x > x - x > 4 - x

or

x > 0 > 4 - x
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by vanesslondon » Fri Jan 25, 2008 1:40 pm
thank you, Stuart!
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by krusteekrab » Tue Jan 29, 2008 11:02 am
another way of looking at it.

6>x+4>4

this means that, if you substitute the value for x as 1 after looking at it more closely.

6 > 1+4 > 4 which is 6>5>4

also if you substitute 0<x<2 which is 0<1<2.
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