Advertisements
Advertisements
प्रश्न
Find n if `""^"n""C"_8 = ""^"n""C"_12`
Advertisements
उत्तर
`""^"n""C"_8 = ""^"n""C"_12`
If nCx = nCy, then either x = y or x = n − y
∴ 8 = 12 or 8 = n − 12
But 8 = 12 is not possible
∴ 8 = n – 12
∴ 8 + 12 = n
∴ 20 = n
∴ n = 20
APPEARS IN
संबंधित प्रश्न
Find n, if `""^21"C"_(6"n") = ""^21"C"_(("n"^2 + 5)`
Find r if `""^11"C"_4 + ""^11"C"_5 + ""^12"C"_6 + ""^13"C"_7 = ""^14"C"_"r"`
A group consists of 9 men and 6 women. A team of 6 is to be selected. How many of possible selections will have at least 3 women?
Five students are selected from 11. How many ways can these students be selected if two specified students are selected?
Find r if 14C2r : 10C2r–4 = 143 : 10
Find the number of ways of drawing 9 balls from a bag that has 6 red balls, 8 green balls, and 7 blue balls so that 3 balls of every colour are drawn
If 20 points are marked on a circle, how many chords can be drawn?
Find the number of diagonals of an n-sided polygon. In particular, find the number of diagonals when n = 12
There are 20 straight lines in a plane so that no two lines are parallel and no three lines are concurrent. Determine the number of points of intersection
Ten points are plotted on a plane. Find the number of straight lines obtained by joining these points if no three points are collinear
Find n if 23C3n = 23C2n+3
Find r if 11C4 + 11C5 + 12C6 + 13C7 = 14Cr
Find the value of `sum_("r" = 1)^4 ""^((21 - "r"))"C"_4`
A committee of 10 persons is to be formed from a group of 10 women and 8 men. How many possible committees will have at least 5 women? How many possible committees will have men in majority?
Five students are selected from 11. How many ways can these students be selected if two specified students are selected?
Five students are selected from 11. How many ways can these students be selected if two specified students are not selected?
Answer the following:
30 objects are to be divided in three groups containing 7, 10, 13 objects. Find the number of distinct ways for doing so.
Answer the following:
Find the number of ways of dividing 20 objects in three groups of sizes 8, 7 and 5
Answer the following:
Four parallel lines intersect another set of five parallel lines. Find the number of distinct parallelograms formed
