# Prove U can't get an constant.

Let us make a series. $$S=1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}..............$$ Prove that this will not converge to a constant.

Extra Credit: Do it without use of calculus.

Note by Utsav Singhal
3 years, 7 months ago

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This is popularly known as the divergence of the Harmonic Series

- 3 years, 7 months ago

The proof that I like is by contradiction.

Suppose $$S$$ converges to a finite number. Then, show that $$S = S + 1$$.

(details to follow).

Staff - 3 years, 4 months ago

Even though the harmonic series does not converge, Is it possible for a partial sum of the series to be an integer?

- 3 years, 4 months ago

Let us make a AM HM inequality. 1/(a-1) + 1/a + 1/(a+1) >= 3/a So we will take its minnimum value... as 3/a Now lets put the values . Leaving 1 then taking 1/2 , 1/3, 1/4 then next three....then next three... So we will get its min value as 1 + 1 + 1/2 + 1/3. ..... to infinity. Then again doing it. 1+1+1+1+1+1+..................to infinite +1/2 + 1/3 + 1/4 .... So its minnimum value comes out to be infinite .

Soorry can't make the solution latex ...!

- 3 years, 7 months ago

It can be done using RATIO TEST.

- 3 years, 7 months ago

Please give the details or any link from where I can learn it.. Thanks.

- 3 years, 7 months ago

- 3 years, 7 months ago

But the limit L here is 1. Therefore, test becomes inconclusive

- 3 years, 4 months ago

2.30 approx

- 3 years, 7 months ago

No no, it is totally wrong . There is no value of it . It will be infinite

- 3 years, 7 months ago