MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

ComplexExpand


It IS TRUE, for integer n > 0 and real x
that
for s = Sum[Binomial[n,k]Cos[x(n-2k],{k,0,n}]

s ==(2 Cos[x])^n
but
the only way to verify that by mathematica
seems to be

(s/.n -> m)/(s/.n -> m-1)
which
results in 2 Cos[x]

ComplexExpand[s]

does not know that s is real of value (2 Cos[x])^n

even if

s = Simplify[Sum[Binomial[n,k]Cos[x(n-2k],{k,0,n}],
Element[x, Reals] && Element[n,Integers] && n > 0]

does not know that s is real of value (2 Cos[x])^n




  • Prev by Date: Re: Integrate 5.0
  • Next by Date: Exit[]
  • Previous by thread: Re: Integrate 5.0
  • Next by thread: Re: ComplexExpand