Math Is Fun Forum

juantheron

Member

Registered: 2011-10-19

Posts: 312

factorial sum

consider a function

  on non-negative integers such that

 

and

  for

Then show that

Answer given in Book is Like this way

So

But I did not Understant Second line

Thanks

Bob

Administrator

Registered: 2010-06-20

Posts: 10,623

Re: factorial sum

hi juantheron,

Looks to me that the line should be:

Then divide by n!

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: factorial sum

Bob is right.Then you can use induction.

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“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

juantheron

Member

Registered: 2011-10-19

Posts: 312

Re: factorial sum

thanks bob and anonim

but how can i get

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: factorial sum

You can show by induction.It is true that:

Now use the formula Bob told you to use:

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“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.