bemath-prove-that-n-1-r-n-1-r-1-n-r-

Question Number 108638 by bemath last updated on 18/Aug/20

\frac{b e m a t h}{★}

p r o v e t h a t (\begin{matrix} n - 1 \\ r \end{matrix}) + (\begin{matrix} n - 1 \\ r - 1 \end{matrix}) = (\begin{matrix} n \\ r \end{matrix})

Answered by bemath last updated on 18/Aug/20

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