Advertisements
Advertisements
प्रश्न
Find n if `""^"n""C"_("n" - 3)` = 84
उत्तर
`""^"n""C"_("n" - 3)` = 84
∴ `("n"!)/(("n"-3)!["n"-("n"-3)]!)` = 84
∴ `("n"("n" - 1)("n" - 2)("n" - 3)!)/(("n" - 3)!xx3!` = 84
∴ n (n – 1) (n – 2) = 84 × 6
∴ n (n – 1) (n – 2) = 9 × 8 × 7
Comparing on both sides, we get n = 9
APPEARS IN
संबंधित प्रश्न
Find the value of `""^20"C"_16 - ""^19"C"_16`
Find n and r if `""^"n""C"_("r" - 1): ""^"n""C"_"r": ""^"n""C"_("r" + 1)` = 20:35:42
If `""^"n""C"_("r" - 1)` = 6435, `""^"n""C"_"r"` = 5005, `""^"n""C"_("r" + 1)` = 3003, find `""^"r""C"_5`.
Find the number of ways of selecting a team of 3 boys and 2 girls from 6 boys and 4 girls.
Find the number of diagonals of an n-shaded polygon. In particular, find the number of diagonals when: n = 10
Find the number of diagonals of an n-shaded polygon. In particular, find the number of diagonals when: n = 12
Find n, if `""^21"C"_(6"n") = ""^21"C"_(("n"^2 + 5)`
Find n, if `""^"n""C"_("n" - 2)` = 15
Find the differences between the largest values in the following: `""^13"C"_r "and" ""^8"C"_r`
Find n and r if nCr–1 : nCr : nCr+1 = 20 : 35 : 42
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
Find the number of ways of selecting a team of 3 boys and 2 girls from 6 boys and 4 girls
Find n if 23C3n = 23C2n+3
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?
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?
Answer the following:
Nine friends decide to go for a picnic in two groups. One group decides to go by car and the other group decides to go by train. Find the number of different ways of doing so if there must be at least 3 friends in each group.
Answer the following:
There are 4 doctors and 8 lawyers in a panel. Find the number of ways for selecting a team of 6 if at least one doctor must be in the team
Answer the following:
Four parallel lines intersect another set of five parallel lines. Find the number of distinct parallelograms formed
If vertices of a parallelogram are respectively (2, 2), (3, 2), (4, 4), and (3, 4), then the angle between diagonals is ______
