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AP EAMCET202123 Aug 2021Morning ShiftMathematicsSets and RelationsActual

If a set A has m elements and set B has n elements and the number of injections from A to B is 2520 . Then, m is equal to

Options

  1. A2
  2. B7
  3. C6
  4. D5

Correct answer

D. 5

Step-by-step solution

Given, |A|=m and |B|=n Total number of injective function from A to B is n ! (n-m) ! Given, n ! (n-m) ! =2520 Total number of injections from A to B= ^n P_m=2520 array ll & ^n P_m=7 6 5 4 3= ^7 P₅ & n=7, m=5 array

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