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# Tag Archives: Integral

## Sophomore’s dream constant

Evaluate the integral

Solution

Let and . The Jacobian is

Hence,

However , since we conclude that

where is Sophomore’s dream constant.

## Logarithmic integral

Evaluate the integral

## An arcosine integral

Evaluate the integral

## A limit

For any nonnegative integer , define

Evaluate the limit .

Solution

Lemma: Let and . It holds that

Proof: The LHS is just the imaginary part of

This is a geometric progression , hence:

The result follows.

Hence,

Now,

## Fractional integral

Let denote the fractional part. Prove that

for the different values of the integer number .

Solution

Let denote the integral,

since if whereas if . Therefore,

except of a countable set whose measure is .