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Thu 27 Jan, 2005 07:39 am
which of these function is bigger than the other :
pi^e and e^pi?
e^pi
pi^e= 22.459157718361045473427152204544
e^pi= 23.140692632779269005729086367949
the idea is to prove it without using any calculator.
You could graph e^x and x^e and show that when x = pi (or x> wherever they cross that is less than pi) one graph is higher than the other.
no, i mean prove it by algebra.
discrete maybe??
how about this:
question,
pi^e ? e^pi meaning that they have some relation but we dont know yet
take the log of both sides (since doing so shouldnt change anything),
ln( pi^e ) ? ln( e^pi )
doing some rearranging we get,
e*ln( pi ) ? pi*ln( e )
and since the base of the log is e we get,
e*ln( pi ) ? pi
and taking the log of both sides one more time should yield,
ln( e*ln( pi ) ) ? ln( pi )
and some more algebra should tell us which side is larger,
ln( ln( pi ) ) + 1 ? ln( pi )
therfore the right side was larger, meaning that e^pi is > pi^e
How do you conclude that ln(ln(pi))+1 < ln(pi)?
the reason is that the ln( ln ( pi ) ) term is a factor of e less than that of just one ln. its like this. you have a number x and you take the ln of it and then you do it again. that is like taking the e-root (square root but in terms of e, like cube root etc) twice vs just taking it once on the other side.
ex: ln( ln( 27 ) ) = 1.1926601162848....
and
ln( 27 ) = 3.2958368660043...
so e^e^1.1926601162848 = e^3.2958368660043 = 27
the ln(ln( term is 1 factor of e away from the ln term.
and in terms of the question at hand, to get back to pi you must take e^e^ to the ln( ln( pi ) ) + 1 to get it back to pi^e state.
another way to look at it is by taking the whole equation to the e. so we get,
ln( pi )*e ? pi. divide be e to get
ln( pi ) ? pi/e. and since in one instance you are only dividing by e and not taking the e-root or taking it to the 1/e power, it should be clear the right hand is larger.
i hope that clears stuff up.
quiksilver wrote:the idea is to prove it without using any calculator.
Then why did God create calculators?
No, it doesn't.
I agree that ln(ln(pi)) < ln(pi)
Other than saying it's so, you haven't demonstrated that ln(ln(pi)) + 1 < ln(pi)
I know that it is. I just don't see the reason in your proof.
markr is right, your proof is not right. you have to get a term that shows obviously which of the functions is bigger.
DrewDad wrote:quiksilver wrote:the idea is to prove it without using any calculator.
Then why did God create calculators?

well the only thing i can think of to do would be this.
e^( ln( ln( pi ) ) + 1 ) ? e^( ln( pi ) ).
ln( pi )*e ? pi.
ln( pi ) ? pi/e.
e^( ln( pi ) ) ? e^( pi/e ).
pi ? e^( pi/e ).
that would be the only thing i can think of at this moment. sorry its not coming to me but i was just trying to help. the difference between the 2 is soo miniscule that i dont think the answer will pop right out at you like say: 2x ? 2x^30000000 ∀x>1 , x<-1 would be
Don't be sorry. You were the only one who offered up anything, and it was so close.