nCr Definitions and Properties
Trending Questions
Q. If nCr−1=36, nCr=84 and nCr+1=126 then r is
- 2
- 3
- none of these
- 1
Q. The digit at units place of the sum (1!)2+(2!)2+(3!)2+.....+(20009)2
- 5
- 0
- 1
- 7
Q. If P (10, r) = 5040, then r =
- 4
- 6
- 8
- 2
Q. A tetrahedron has vertices at O(0, 0, 0), A(1, 2, 1), B(2, 1, 3) and C(−1, 1, 2). Then the angle between the faces OAB and ABC will be
![616919_86fde102254d4059a8a98c136dbbaae6.JPG](https://search-static.byjusweb.com/question-images/toppr_ext/questions/616919_86fde102254d4059a8a98c136dbbaae6.JPG)
- 120∘
- cos−1(1731)
- 30∘
- 90∘
Q. The value of ∑10r=1r.rPr =
- 11!
- 11! - 1
- 11! + 1
- 11! - 11
Q.
If 56Pr+6:54Pr+3 = 30800:1, then r =
41
31
51
40
Q. The value of the expression 47C4+∑5j=1 52−jC3 is
- 47C5
- 52C5
- 52C4
- None of these
Q. The value of limn→∞(3n+5n+7n)1/n equals
- 3
- 7
- 5
- ∞
Q. Find the number of ways in which AAABBB can be placed in the squares of Fig as shown, so that no row remains empty.
![144958_3d20740d769942809f8ae88fb277b487.png](https://search-static.byjusweb.com/question-images/toppr_ext/questions/144958_3d20740d769942809f8ae88fb277b487.png)
![144958_3d20740d769942809f8ae88fb277b487.png](https://search-static.byjusweb.com/question-images/toppr_ext/questions/144958_3d20740d769942809f8ae88fb277b487.png)
Q.
Find the number of diagonals from one vertex for a polygon having 25 sides.
- 22
- 24
- 20
- 23
Q. If the letters of the word ASSASSIN are arranged at random in row, the probability that no two S’s occur together is:
- 35
- 128
- 135
- 114