Problem with inequality and number e Prove that, for every positive integer n, the following inequality holds: n{n! xx e}<1,where {x} denotes the fractional part function applied to number x. I can;t think of any solution.

Davirnoilc

Davirnoilc

Answered question

2022-11-11

Problem with inequality and number e
Prove that, for every positive integer n, the following inequality holds:
where { x } denotes the fractional part function applied to number x
I can;t think of any solution.

Answer & Explanation

Falpo359

Falpo359

Beginner2022-11-12Added 15 answers

Because
e = 2 + 1 2 ! + 1 3 ! + . . . + 1 n ! + . . . =
= 2 + 1 2 ! + 1 3 ! + . . . + 1 n ! + 1 ( n + 1 ) ! ( 1 + 1 n + 2 + 1 ( n + 2 ) ( n + 3 ) + . . . ) <
= 2 + 1 2 ! + 1 3 ! + . . . + 1 n ! + 1 ( n + 1 ) ! ( 1 + 1 n + 1 + 1 ( n + 1 ) 2 + . . . ) =
= 2 + 1 2 ! + 1 3 ! + . . . + 1 n ! + 1 ( n + 1 ) ! 1 1 1 n + 1 =
= 2 + 1 2 ! + 1 3 ! + . . . + 1 n ! + 1 n n ! .
Thus, { e n ! } < 1 n and we are done!

Do you have a similar question?

Recalculate according to your conditions!

Ask your question.
Get an expert answer.

Let our experts help you. Answer in as fast as 15 minutes.

Didn't find what you were looking for?