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Question: Answered & Verified by Expert
The number of ways in which 10 balls can be selected from 10 identical green balls, 10 identical blue balls and 9 identical red balls are
MathematicsPermutation CombinationJEE Main
Options:
  • A 63
  • B 64
  • C 65
  • D 66
Solution:
2153 Upvotes Verified Answer
The correct answer is: 65
Required number of ways = coefficient of x10 in
x0+x1+x2+....+x102x0+x1+x2+....+x9
= coeff. of x10 in 1-x111-x21-x101-x
= coeff. of x10 in 1x31x1121x10
= coeff. of x10 in 1x31+x222x111x10
= coeff. of x10 in 1x31+x222x11x10x32+2x21
= coeff. of x10 in 1x31x102x11+2x21+x22x32
= coeff. of x10 in 1x3 coeff. of x0 in 1x3
=10+3-1C10-1=12C10-1=12×1121=65

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