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heshamelaziry
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...1/x...
Just let x = a number and plug it in!
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Factorial
Source: Beat The GMAT — Problem Solving |
if you want to do it the algebraic way, you can always do this:
(x-1)!/x!
We know that x! is equal to x*(x-1)*(x-2).. and so on.
(x-1)! is equal to (x-1)*(x-2)*(x-3).. and so on.
(x-1)*(x-2)*(x-3)*.../(x)*(x-1)*(x-2)*...=1/x.
I suggest using the plugging in the number method to solve this problem so one can visualize it better.
(x-1)!/x!
We know that x! is equal to x*(x-1)*(x-2).. and so on.
(x-1)! is equal to (x-1)*(x-2)*(x-3).. and so on.
(x-1)*(x-2)*(x-3)*.../(x)*(x-1)*(x-2)*...=1/x.
I suggest using the plugging in the number method to solve this problem so one can visualize it better.
