Answer check, Hyperbolic trig identity (proof)

[bakin]

Homework Statement

Evaluate the integral:
(int sign) Sech³xTanhx dx

Homework Equations

Derivative of Sechx = -(SechxTanhx)

The Attempt at a Solution

Rewrite as:
Sech²xSechxTanhx

U=sechx
Du = -(SechxTanhx)dx
-Du = SechxTanhx dx
replace into integral

-(integral sign) U²du

Evaluate:
-U³ / 3

answer = -Sech³x / 3

? It just seems like there should be more to it. What do you guys think?

 

[neutrino]

Indeed there is more to it - a constant of integration.

 

[bakin]

grr

Thanks

 

[dextercioby]

it would have been much simpler if you had written everything in terms of sinh and cosh.

My 2ç