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 `""^80"C"_2`
After a meeting, every participant shakes hands with every other participants. If the number of handshakes is 66, find the number of participants in the meeting.
Ten points are plotted on a plane. Find the number of straight lines obtained by joining these points if four points are collinear.
find the value of `sum_("r" = 1)^4 ""^(21 - "r")"C"_4 + ""^17"C"_5`
Find the differences between the largest values in the following: `""^14"C"_r "and" ""^12"C"_r`
In how many ways can a boy invite his 5 friends to a party so that at least three join the party?
Find the number of diagonals of an n-sided polygon. In particular, find the number of diagonals when n = 10
Find the number of diagonals of an n-sided polygon. In particular, find the number of diagonals when n = 8
Find the number of triangles formed by joining 12 points if no three points are collinear
Find n if 21C6n = `""^21"C"_(("n"^2 + 5))`
Find r if 11C4 + 11C5 + 12C6 + 13C7 = 14Cr
In how many ways can a boy invite his 5 friends to a party so that at least three join the party?
Select the correct answer from the given alternatives.
The number of ways in which 5 male and 2 female members of a committee can be seated around a round table so that the two females are not seated together is
Answer the following:
Ten students are to be selected for a project from a class of 30 students. There are 4 students who want to be together either in the project or not in the project. Find the number of possible selections
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:
Find the number of ways of dividing 20 objects in three groups of sizes 8, 7 and 5
If vertices of a parallelogram are respectively (2, 2), (3, 2), (4, 4), and (3, 4), then the angle between diagonals is ______
What is the probability of getting a “FULL HOUSE” in five cards drawn in a poker game from a standard pack of 52-cards?
[A FULL HOUSE consists of 3 cards of the same kind (eg, 3 Kings) and 2 cards of another kind (eg, 2 Aces)]
