Let A and B be two nite sets. Let BA denote the set of all functions from A to B. (a) Prove that IBAI = IBI'A' (b) Let I C BA denote the subset of...

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This question is from mathematical reasoning class

2. Let A and B be two finite sets. Let BA denote the set of all functionsfrom A to B.(a) Prove that IBAI = IBI'A' (b) Let I C BA denote the subset of all injective functions from A tcB. Show that \I|=n(n—l)...(n—m+l),wheren: |B| andm: |A|.