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Prove that ((2n)!)/(n!) =2^(n) xx{1xx3x...

Prove that ` ((2n)!)/(n!) =2^(n) xx{1xx3xx5xx...xx(2n-1)}. `

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Verified by Experts

We have
` ((2n)!)/(n!) =({1xx2xx3xx4xx5xx...xx(2n-2)xx(2n-1)xx 2n})/(n!) `
`=({1xx3xx5xx...xx(2n-1)}xx{2xx4xx6xx...xx(2n-2)xx2n})/(n!) `
`=({1xx3xx5xx...xx(2n-1)}xx2^(n)xx{1xx2xx3xx...xxn})/(n!) `
` =({1xx3xx5xx...xx(2n-1)}xx2^(n)xx (n!))/(n!) `
` =2^(n)xx{1xx3xx5xx...xx(2n-1)}.`
Hence, `((2n)!)/(n!)= 2^(n)xx{1xx3xx5xx...xx(2n-1)}. `
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RS AGGARWAL-PERMUTATIONS-EXERCISE 8H (Very-Short-Answer Questions)
  1. Prove that ((2n)!)/(n!) =2^(n) xx{1xx3xx5xx...xx(2n-1)}.

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  2. If (n+1)! =12 xx [(n-1)!], find the value of n.

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  3. If (1)/(4!) + (1)/(5!)=(x)/(6!), find the value of x.

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  4. How many 3-digit numbers are there with no digit repeated?

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  5. How many 3-digit numbers above 600 can be formed by using the digits 2...

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  6. How many numbers divisible by 5 and lying between 4000 and 5000 can b...

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  7. In how many ways can the letters of the word 'CHEESE' be arranged?

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  8. In how many ways can the letters of the word 'PERMUTATIONS' be arrang...

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  9. How many different words can be formed by using all the letters of the...

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  10. How many permutations of the letters of the word 'APPLE' are there?

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  11. How many words can be formed by the letters of the word 'SUNDAY'?

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  12. In how many ways can 4 letters be posted in 5 letter boxes?

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  13. In how many ways can 4 women draw water from 4 taps, if no tap remains...

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  14. How many 5-digit numbers can be formed by using the digits 0, 1 and 2?

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  15. In how many ways can 5 boys and 3 girls be seated in a row so that eac...

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  16. A child has plastic toys bearing the digits 4, 4 and 5. How many 3-dig...

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  17. In how may ways can the letters of the word 'PENCIL' be arranged so th...

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