The integral of 1/(e^x+e^-x) with respect to x(ie.dx) thank you in advance[/tex]
G Guest Guest Aug 28, 2006 #1 The integral of 1/(e^x+e^-x) with respect to x(ie.dx) thank you in advance[/tex]
G galactus Super Moderator Staff member Joined Sep 28, 2005 Messages 7,216 Aug 28, 2006 #2 Does it help you in knowing that \(\displaystyle \L\\\frac{1}{e^{x}+e^{-x}}=\frac{1} {2}sech(x)\) Probably not, huh?. \(\displaystyle \L\\\int\frac{1}{e^{x}+e^{-x}}dx\) Factor \(\displaystyle \L\\e^{x}\) out of the denominator: \(\displaystyle \L\\\int\frac{1}{e^{x}(1+e^{-2x})}dx\) Let \(\displaystyle \L\\u=-e^{-x};\;\ du=e^{-x}dx=\frac{1}{e^{x}}dx\) \(\displaystyle \L\\\int\frac{1}{1+u^{2}}du\)
Does it help you in knowing that \(\displaystyle \L\\\frac{1}{e^{x}+e^{-x}}=\frac{1} {2}sech(x)\) Probably not, huh?. \(\displaystyle \L\\\int\frac{1}{e^{x}+e^{-x}}dx\) Factor \(\displaystyle \L\\e^{x}\) out of the denominator: \(\displaystyle \L\\\int\frac{1}{e^{x}(1+e^{-2x})}dx\) Let \(\displaystyle \L\\u=-e^{-x};\;\ du=e^{-x}dx=\frac{1}{e^{x}}dx\) \(\displaystyle \L\\\int\frac{1}{1+u^{2}}du\)
skeeter Elite Member Joined Dec 15, 2005 Messages 3,216 Aug 28, 2006 #3 \(\displaystyle \L \frac{1}{e^x + e^{-x}} =\) \(\displaystyle \L \frac{1}{\frac{e^{2x}}{e^x} + \frac{1}{e^x}} =\) \(\displaystyle \L \frac{1}{\frac{e^{2x} + 1}{e^x}} =\) \(\displaystyle \L \frac{e^x}{e^{2x} + 1}\) \(\displaystyle \L \int \frac{e^x}{e^{2x} + 1} dx = arctan(e^x) + C\)
\(\displaystyle \L \frac{1}{e^x + e^{-x}} =\) \(\displaystyle \L \frac{1}{\frac{e^{2x}}{e^x} + \frac{1}{e^x}} =\) \(\displaystyle \L \frac{1}{\frac{e^{2x} + 1}{e^x}} =\) \(\displaystyle \L \frac{e^x}{e^{2x} + 1}\) \(\displaystyle \L \int \frac{e^x}{e^{2x} + 1} dx = arctan(e^x) + C\)