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InterviewSolution
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A function is defined by mapping f : A → B such that A contains m elements and B contains n elements and 1≤n≤m then number of onto functions are ________(a) r=1∑^r=n ^nCr (-1)^n-r r^m(b) r=1∑^r=n ^nCr (-1)^n-r r^n(c) r=1∑^r=n ^nCr (-1)^m-r r^n(d) None of the mentionedI have been asked this question in unit test.The above asked question is from Number of Functions topic in chapter Basic Structures: Sets, Functions, Sequences, Sums and Matrices of Discrete Mathematics |
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Answer» CORRECT answer is (a) r=1∑^r=N ^NCR (-1)^n-r r^m Explanation: The number of onto function is equal tpo the COFFECIENT of x^m in m!(e^x – 1)n. |
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