Sorry I don't know how to type this in mathematical symbols. Prove that: the summation from r=0 to n of (C(n,r))(a-1)^r = a^n Thanks for any help I can get
Follow Math Help Forum on Facebook and Google+
Use the binomial theorem. $\displaystyle \left( {x + y} \right)^n = \sum\limits_{r = 0}^n {\binom{n}{r}x^r y^{n - r} } $ Let $\displaystyle x=(a-1)~\&~y=1$
View Tag Cloud