ExamBro
ExamBro
JEE Advanced · Mathematics · 22. Functions

Let X be a set with exactly 5 elements and Y be a set with exactly 7 elements. If α is the number of one-one functions from XY and β is the number of onto functions from YX, then the value of 15!β-α is _____-.

  1. A 110
  2. B 152
  3. C 119
  4. D 201
Verified Solution

Answer & Solution

Correct Answer

(C) 119

Step-by-step Solution

Detailed explanation

nX=5
nY=7
α Number of one-one function =7C5×5!
β Number of onto function Y to X

So, β=7!3!4!×5!+7!2!33!×5!=7C3+3. 7C35!=4×7C3×5!
β-α5!=4×7C3-7C5=4×35-21=119
From JEE Advanced
Explore more questions on app