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 Post subject: Logic/ Statements and Quantifiers
PostPosted: Thu, 10 Mar 2011 16:14:35 UTC 
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Joined: Wed, 9 Mar 2011 22:13:06 UTC
Posts: 6
Hello!
I have a following problem to solve:

The statement "For SOME real number x, X^2 (x to the second power) is greater or equal to 0" is true.
However, your friend does not understand why, since he claims that X^2 is greater or equal to 0 for ALL real numbers X and not just for SOME. How would you explain his misconception to him?

I know that some means at least one, which makes the first statement true. But on the other hand, I need to agree with this friend because I cannot come with a real number for which this equation would be false. Doesn't is mean that it is true for ALL real numbers then?

Could someone please help me with this. Thank you!


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 Post subject: Re: Logic/ Statements and Quantifiers
PostPosted: Thu, 10 Mar 2011 18:17:02 UTC 
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magwoj wrote:
Hello!
I have a following problem to solve:

The statement "For SOME real number x, X^2 (x to the second power) is greater or equal to 0" is true.
However, your friend does not understand why, since he claims that X^2 is greater or equal to 0 for ALL real numbers X and not just for SOME. How would you explain his misconception to him?

I know that some means at least one, which makes the first statement true. But on the other hand, I need to agree with this friend because I cannot come with a real number for which this equation would be false. Doesn't is mean that it is true for ALL real numbers then?

Could someone please help me with this. Thank you!


If it's true for all of them, then it's definitely true for some of them, both statements are true. It's like saying some NBA players know how to play basketball. Surely this is true, it's just also true for all of them. You shouldn't let the fact that you're talking about math make you doubt how logic works, logic is applicable everywhere.

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 Post subject:
PostPosted: Fri, 11 Mar 2011 05:04:02 UTC 
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Math Cadet

Joined: Wed, 9 Mar 2011 22:13:06 UTC
Posts: 6
Thank you. I think I was just over-analyzing it too much and I thought there was more to it than that :)


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