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Question Number 85187 by mathocean1 last updated on 19/Mar/20
$${Show}\:{that}\:\forall\:{n},\:{p}\:\in\:\mathbb{N}^{\ast\:} \\ $$$${C}_{{n}−\mathrm{1}} ^{\:{p}−\mathrm{1}} +{C}_{{n}−\mathrm{1}} ^{\:{p}} ={C}_{{n}} ^{\:{p}} \\ $$