Write the given hyperbolic function as simply as possible

chwala
Gold Member
Messages
2,827
Reaction score
415
Homework Statement
##\dfrac{e^x}{1+e^{2x}}##
Relevant Equations
hyperbolic equations
My take;

##2\cosh x = e^x +e^{-x}##

I noted that i could multiply both sides by ##e^x## i.e

##e^x⋅2\cosh x = e^x(e^x +e^{-x})##

##e^x⋅2\cosh x = e^{2x}+1##

thus,

##\dfrac{e^x}{1+e^{2x}}=\dfrac{\cosh x + \sinh x}{e^x⋅2\cosh x}##

##= \dfrac{\cosh x + \sinh x}{(\cosh x + \sinh x)⋅2\cosh x}##

##=\dfrac{1}{2\cosh x}##
any other approach is welcome.
 
Last edited by a moderator:
Physics news on Phys.org
chwala said:
Homework Statement:: ##\dfrac{e^x}{1+e^{2x}}##
Relevant Equations:: hyperbolic equations

both sides
There are no 'sides'
There is no 'equation'

You post an expression. If you divide numerator and denominator by ##e^x## you see that you can rewrite the expression as ##1\over 2\cosh x##: the numerator is now ##1## and the denominator is now ##2\cosh x##. There is no need to write ##1## as ##\cosh x + \sinh x##

Cheers !

##\ ##
 
BvU said:
There are no 'sides'
There is no 'equation'

You post an expression. If you divide numerator and denominator by ##e^x## you see that you can rewrite the expression as ##1\over 2\cosh x##: the numerator is now ##1## and the denominator is now ##2\cosh x##. There is no need to write ##1## as ##\cosh x + \sinh x##

Cheers !

##\ ##
...seen that...correct man ! it's an expression ...i just posted exactly as it appears on textbook...i should have checked that or rather introduced ##f(x)## on the lhs.
 
BvU said:
There is no need to write ##1## as ##\cosh x + \sinh x##
the more so because it is totally incorrect :biggrin: ! My bad, I should have written "##e^x## as ##\cosh x + \sinh x## "
 
Thread 'Use greedy vertex coloring algorithm to prove the upper bound of χ'
Hi! I am struggling with the exercise I mentioned under "Homework statement". The exercise is about a specific "greedy vertex coloring algorithm". One definition (which matches what my book uses) can be found here: https://people.cs.uchicago.edu/~laci/HANDOUTS/greedycoloring.pdf Here is also a screenshot of the relevant parts of the linked PDF, i.e. the def. of the algorithm: Sadly I don't have much to show as far as a solution attempt goes, as I am stuck on how to proceed. I thought...
Back
Top