Re: Different answers in mathematica and my calculator.

*To*: mathgroup at smc.vnet.net*Subject*: [mg125593] Re: Different answers in mathematica and my calculator.*From*: Peter Pein <petsie at dordos.net>*Date*: Tue, 20 Mar 2012 02:22:38 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jk70c1$12t$1@smc.vnet.net>

Am 19.03.2012 11:04, schrieb Nile: > 4/(3Power[2(-2)+3, (3)^-1]) > > I get -(4/3) (-1)^(2/3) in Mathematica but only -4/3 on my calculator. > powers with non-integer exponents are not unique in the domain of complex numbers. Try Root[]: 4/(3 Root[#^3 - (2 (-2) + 3) &, 1]) > > N[Sec[8/(8 Sqrt[2])]]/Degree to get Cos^-1 of 8/(8 Sqrt[2]) and it gives me 75 deg instead of 45... > > I'm not sure what I'm doing wrong, I tried in Wolfram Alpha and it gives me the same thing. I am afraid, you mixed the inverse function cos^(-1)(x) with the reciprocal (cos(x))^(-1). Use ArcCos and FunctionExpand (the latter to convert Degree to Pi/180): ArcCos[8/(8 Sqrt[2])]/Degree // FunctionExpand > > Thank you. > > -Francis >