Mathematics
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OpenStudy (anonymous):
what is the supremum of set of real nos???
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terenzreignz (terenzreignz):
You know what supremum means?
OpenStudy (anonymous):
yes least uper bound
terenzreignz (terenzreignz):
As a matter of fact, yes.
Can we, in fact, *bound* the set of real numbers?
OpenStudy (anonymous):
i think no....but i have read R satisfies the property of completeness
OpenStudy (anonymous):
and according to this property a bounded above set has a supremum
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OpenStudy (anonymous):
now what is this???
terenzreignz (terenzreignz):
It means... if a set has an upper bound, then it has a least upper bound (supremum)
terenzreignz (terenzreignz):
The converse is obviously true...
If a set has a least upper bound, then it has an upper bound... (proof: duh XD)
terenzreignz (terenzreignz):
So... suppose the set of real numbers has an upper bound..
OpenStudy (anonymous):
then plz tell me what is the sup of R?
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terenzreignz (terenzreignz):
Let's suppose there exists a real number a which is the supremum of R.
terenzreignz (terenzreignz):
Then a+1 is also a real number because the set of real numbers is closed under addition.
terenzreignz (terenzreignz):
a < a+1
Which already contradicts the assumption of the EXISTENCE of a supremum.
OpenStudy (anonymous):
what is its upper bound?? infinity??? i think infinity can not be sup
terenzreignz (terenzreignz):
Of course not, infinity is not a number. :D
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OpenStudy (anonymous):
then suprimum of R?
terenzreignz (terenzreignz):
Does it even have one?
OpenStudy (anonymous):
what does it mean...i could'nt understand?
terenzreignz (terenzreignz):
Think of it this way... a supremum is like a maximum value...
terenzreignz (terenzreignz):
So... does the set of all real numbers have a maximum?
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OpenStudy (anonymous):
yes but this is what i want to ask what is this max no??
terenzreignz (terenzreignz):
Give it a good think... what is the biggest number?
OpenStudy (anonymous):
do you know the ans???
terenzreignz (terenzreignz):
As to what is the biggest number?
OpenStudy (anonymous):
i dont know
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OpenStudy (anonymous):
can u tell??
OpenStudy (anonymous):
can u???
OpenStudy (anonymous):
what happens???