Stage: 5 Challenge Level: 
Prove that the sum
$$ \sum_{t=0}^m {(-1)^t\over t!(m-t)!} = 0 $$
Powers & roots. Manipulating algebraic expressions/formulae. alphas. Binomial Theorem. Mathematical reasoning & proof. Inequality/inequalities. Summation of series. epsilons. Quadratic equations. Stage 5 - Reviewed 2012.
Published January 2003.
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