i got confused by this question seems relatively simple but dnt get it. how many non-injective functions are there from {1,2,3,4} to {1,2,3,4,5}? How many non-injective functions are there from {1,2,3,4,5} to {1,2,3,4}? thanks.
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Using a usual notation for sets of functions , then if there are functions from A to B. Of those are injections. So how many non-injections are there? There are no injections from B to A. WHY?
because B has more elements than A when you say (5)(4)(3)(2)..what do you mean.thanks
Originally Posted by skystar when you say (5)(4)(3)(2)..what do you mean.thanks Multiply: (5)(4)(3)(2)=120!
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