Advertisements
Advertisements
प्रश्न
If n +5Pn +1 =\[\frac{11 (n - 1)}{2}\]n +3Pn, find n.
उत्तर
n +5Pn +1 =11(n-1)2n +3Pn
\[ \Rightarrow \frac{\left( n + 5 \right)!}{4!} = \frac{11\left( n - 1 \right)}{2} \times \frac{\left( n + 3 \right)!}{3!}\]
\[ \Rightarrow \frac{\left( n + 5 \right)!}{\left( n + 3 \right)!} = \frac{11\left( n - 1 \right)}{2} \times \frac{4!}{3!}\]
\[ \Rightarrow \frac{\left( n + 5 \right)\left( n + 4 \right)\left( n + 3 \right)!}{\left( n + 3 \right)!} = \frac{11\left( n - 1 \right)}{2} \times \frac{4 \times 3!}{3!}\]
\[ \Rightarrow \left( n + 5 \right)\left( n + 4 \right) = 22\left( n - 1 \right)\]
\[ \Rightarrow n^2 + 9n + 20 = 22n - 22\]
\[ \Rightarrow n^2 - 13n + 42 = 0\]
\[ \Rightarrow n = 7, 6\]
APPEARS IN
संबंधित प्रश्न
Convert the following products into factorials:
3 · 6 · 9 · 12 · 15 · 18
Convert the following products into factorials:
1 · 3 · 5 · 7 · 9 ... (2n − 1)
If \[\frac{(2n)!}{3! (2n - 3)!}\] and \[\frac{n!}{2! (n - 2)!}\] are in the ratio 44 : 3, find n.
Prove that:
\[\frac{n!}{(n - r)! r!} + \frac{n!}{(n - r + 1)! (r - 1)!} = \frac{(n + 1)!}{r! (n - r + 1)!}\]
Four books, one each in Chemistry, Physics, Biology and Mathematics, are to be arranged in a shelf. In how many ways can this be done?
How many 3-digit even number can be made using the digits 1, 2, 3, 4, 5, 6, 7, if no digits is repeated?
In how many ways can the letters of the word 'STRANGE' be arranged so that
the vowels never come together?
How many words can be formed from the letters of the word 'SUNDAY'? How many of these begin with D?
How many permutations can be formed by the letters of the word, 'VOWELS', when
each word begins with O and ends with L?
How many permutations can be formed by the letters of the word, 'VOWELS', when
all vowels come together?
How many words can be formed out of the letters of the word 'ARTICLE', so that vowels occupy even places?
In how many ways can a lawn tennis mixed double be made up from seven married couples if no husband and wife play in the same set?
m men and n women are to be seated in a row so that no two women sit together. if m > n then show that the number of ways in which they can be seated as\[\frac{m! (m + 1)!}{(m - n + 1) !}\]
How many words (with or without dictionary meaning) can be made from the letters in the word MONDAY, assuming that no letter is repeated, if all letters are used but first is vowel.
Find the number of words formed by permuting all the letters of the following words:
ARRANGE
Find the number of words formed by permuting all the letters of the following words:
PAKISTAN
Find the number of words formed by permuting all the letters of the following words:
RUSSIA
Find the number of words formed by permuting all the letters of the following words:
SERIES
How many words can be formed with the letters of the word 'PARALLEL' so that all L's do not come together?
How many numbers can be formed with the digits 1, 2, 3, 4, 3, 2, 1 so that the odd digits always occupy the odd places?
How many number of four digits can be formed with the digits 1, 3, 3, 0?
How many different numbers, greater than 50000 can be formed with the digits 0, 1, 1, 5, 9.
In how many ways can the letters of the word
"INTERMEDIATE" be arranged so that:the vowels always occupy even places?
Prove that the product of 2n consecutive negative integers is divisible by (2n)!
For all positive integers n, show that 2nCn + 2nCn − 1 = `1/2` 2n + 2Cn+1
Let r and n be positive integers such that 1 ≤ r ≤ n. Then prove the following:
Let r and n be positive integers such that 1 ≤ r ≤ n. Then prove the following:
There are 10 persons named\[P_1 , P_2 , P_3 , . . . . , P_{10}\]
Out of 10 persons, 5 persons are to be arranged in a line such that in each arrangement P1 must occur whereas P4 and P5 do not occur. Find the number of such possible arrangements.
How many words, with or without meaning can be formed from the letters of the word 'MONDAY', assuming that no letter is repeated, if (i) 4 letters are used at a time
How many words, with or without meaning can be formed from the letters of the word 'MONDAY', assuming that no letter is repeated, if all letters are used at a time
Find the number of permutations of n different things taken r at a time such that two specified things occur together?
Write the value of\[\sum^6_{r = 1} \ ^{56 - r}{}{C}_3 + \ ^ {50}{}{C}_4\]
Write the maximum number of points of intersection of 8 straight lines in a plane.
Write the total number of words formed by 2 vowels and 3 consonants taken from 4 vowels and 5 consonants.
