Previous in Permutation and Combination Next in Permutation and Combination
Question Number 171845 by Mikenice last updated on 21/Jun/22
$${n}_{{c}_{{r}+\mathrm{1}} } +\:{n}_{{c}_{{r}} } ={n}+\mathrm{1}_{{c}_{{r}\:\:.{solve}\:{for}\:\:{n}\:{and}\:{r}.} } \\ $$