Home
Class 11
MATHS
""^nCr+2^nC(r+1)+""^nC(r+2) is equal to ...

`""^nC_r+2^nC_(r+1)+""^nC_(r+2)` is equal to `(2 le r le n)`

A

`^(2n)C_(r+2)`

B

`^(n+1)C_(r-1)`

C

`^(n+2)C_(r+2)`

D

none of these

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

  • PERMUTATIONS AND COMBINATIONS

    JBD PUBLICATION|Exercise EXAMPLE|59 Videos

  • MODEL PAPER (8)

    JBD PUBLICATION|Exercise EXERICSE|41 Videos

  • PRINCIPLE OF MATHEMATICAL INDUCTION

    JBD PUBLICATION|Exercise EXAMPLE|11 Videos

Similar Questions

Explore conceptually related problems

nC_r+^nC_(r+1)=^(n+1)C_x , then x is equal to:

If ^nC_12=^nC_8 , then n is equal to:

The vaule of sum_(r=0)^(n-1) (""^(C_(r))/(""^(n)C_(r) + ""^(n)C_(r +1))) is equal to

The value of ("^nC_r)/(^nC_(r+1)) is equal to:

The value of ("^nC_r)/('^nC_(r-1)) is equal to:

sum_(r=1)^(n) {sum_(r1=0)^(r-1) ""^(n)C_(r) ""^(r)C_(r_(1)) 2^(r1)} is equal to

The sum sum_(r=0)^n (r+1) (C_r)^2 is equal to :

If ""^nC_r= ""^nC_s , then n is:

Prove that "^nC_r+2 ^(n)C_(r-1)+ ^(n)C_(r-2) = ^(n+2)C_r .

If ""^nC_r denotes the number of combinations of n things taken r at a time, then the expression ""^nC_(r+1)+""^nC_(r-1)+ 2xx""^nC_r equals :

JBD PUBLICATION-PERMUTATIONS AND COMBINATIONS-EXAMPLE
  1. ""^nCr+2^nC(r+1)+""^nC(r+2) is equal to (2 le r le n)

    Text Solution

    |

  2. Find the number of different 8-letter arrangenients that can be made f...

    Text Solution

    |

  3. A class has 30 students, In how many ways can three prizes be awarded ...

    Text Solution

    |

  4. A class has 30 students, In how many ways can three prizes be awarded ...

    Text Solution

    |

  5. A coin is tossed 3 times and the outcomes are recorded. How many possi...

    Text Solution

    |

  6. How many 3-digit even numbers can be formed from the digits 1, 2, 3, 4...

    Text Solution

    |

  7. How many 3-digit even numbers can be formed from the digits 1, 2, 3, 4...

    Text Solution

    |

  8. How many 3-digit numbers are there without repetition?

    Text Solution

    |

  9. If 1/(6!)+1/(7!)=x/(8!), find x

    Text Solution

    |

  10. Show that (2n)!/n!=[1.3.5……………….(2n-1)]2^n.

    Text Solution

    |

  11. How many 4-digit numbers are there with no digit repeated?

    Text Solution

    |

  12. How many numbers are there between 1000 and 9999 so that no digit is r...

    Text Solution

    |

  13. In how many ways can 5 girls be seated in a row so that two girls Ridh...

    Text Solution

    |

  14. In how many ways can 5 girls be seated in a row so that two girls Ridh...

    Text Solution

    |

  15. Find the number of permutations of the letters of word 'DISSIMILAR' wh...

    Text Solution

    |

  16. If nC6=nC2, find ^nC2.

    Text Solution

    |

  17. If 10Cr=^10C2 find the values of r.

    Text Solution

    |

  18. A bag contains 5 black and 6 red balls. Determine the number of ways i...

    Text Solution

    |

  19. In how many ways can a student choose a programme of 5 courses if 9 co...

    Text Solution

    |

  20. How many chords can be drawn through 21 points on a circle?

    Text Solution

    |

  21. Out of 18 points in a plane, no three are in the same straight line ex...

    Text Solution

    |