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# If x is a positive integer, what is the result when (x + 1)!

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Joined: 09 Dec 2013
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If x is a positive integer, what is the result when (x + 1)!  [#permalink]

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Updated on: 29 May 2014, 04:02
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35% (medium)

Question Stats:

71% (01:27) correct 29% (01:15) wrong based on 150 sessions

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If x is a positive integer, what is the result when (x + 1)! is divided by (x - 1)! ?

(1) (x - 1)! = 720
(2) x(x + 1) = 56

Originally posted by arjoban on 29 May 2014, 03:01.
Last edited by Bunuel on 29 May 2014, 04:02, edited 1 time in total.
Renamed the topic and edited the question.
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Re: If x is a positive integer, what is the result  [#permalink]

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29 May 2014, 04:05
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arjoban wrote:
If x is a positive integer, what is the result when (x + 1)! is divided by (x - 1)! ?
(1) (x - 1)! = 720
(2) x(x + 1) = 56

Sol:The above expression can be written as
$$\frac{(x+1)!}{(x-1)!}$$---------> $$\frac{(x+1)*x(x-1)!}{(x-1)!}$$

So we need to find what is the result of x*(x+1)

St1: (x-1)!=720, we know 6!=720 so x=7. We can find x(x+1). Sufficient
St 2 : x*(x+1)= 56.....straight away gives what we want. Sufficient

Ans is D
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Re: If x is a positive integer, what is the result when (x + 1)!  [#permalink]

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27 Oct 2015, 13:28
arjoban wrote:
If x is a positive integer, what is the result when (x + 1)! is divided by (x - 1)! ?

(1) (x - 1)! = 720
(2) x(x + 1) = 56

Statement 1. Factorial of some number is 720=8*9*10=2*2*2*2*3*3*5=6*5*4*3*2*1 hence 6!-720 =>x=7
Statment 2. Product of two consecutive numbers is 56. 56=7*8. Again x=7 hence sufficient.
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If x is a positive integer, what is the result when (x + 1)! is divide  [#permalink]

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11 Feb 2017, 10:46
If x is a positive integer, what is the result when (x + 1)! is divided by (x - 1)! ?

(1) (x - 1)! = 720
(2) x(x + 1) = 56
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Re: If x is a positive integer, what is the result when (x + 1)!  [#permalink]

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11 Feb 2017, 11:49
If x is a positive integer, what is the result when (x + 1)! is divided by (x - 1)! ?

(1) (x - 1)! = 720
(2) x(x + 1) = 56

Merging topics. p'lease refer to the discussion above.
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Re: If x is a positive integer, what is the result when (x + 1)! &nbs [#permalink] 11 Feb 2017, 11:49
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# If x is a positive integer, what is the result when (x + 1)!

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