Re: integration

*To*: mathgroup at smc.vnet.net*Subject*: [mg95999] Re: [mg95952] integration*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Sat, 31 Jan 2009 06:45:32 -0500 (EST)*References*: <200901301047.FAA06620@smc.vnet.net>*Reply-to*: drmajorbob at longhorns.com

For instance... Integrate[1/Sqrt[x^2 - b^2], x] Log[2 (x + Sqrt[-b^2 + x^2])] but Log[2 (x + Sqrt[-b^2 + x^2])] - Log[x + Sqrt[-b^2 + x^2]] // Simplify Log[2] That's probably the kind of difference you're seeing between the online answer and the one you expect. -Log[b] is just a constant, after all. Bobby On Fri, 30 Jan 2009 04:47:06 -0600, <t.p.nixon at open.ac.uk> wrote: > Hi, I don't use mathematica but the other day I wanted to solve an > integral and I'm out of practice so I went on-line to a mathematica > based integrator. > > http://integrals.wolfram.com/index.jsp > > I typed in 1/sqrt(x^2-b^2) this should have an integral of cosh^-1(x/ > b). Ok, so it didn't recognize cosh but its answer was (I think) > wrong. it comes back with ln(x+sqrt(x^2-b^2)) it seems to have > overlooked a quotient of b in the log. > > Is this a general problem with mathematica or just the on-line version > or is it me? > -- DrMajorBob at longhorns.com

**References**:**integration***From:*t.p.nixon@open.ac.uk