Solve Series Convergence Problem: Find Sum

  • Thread starter Thread starter Yae Miteo
  • Start date Start date
  • Tags Tags
    Series
Yae Miteo
Messages
41
Reaction score
0

Homework Statement



Determine whether the series is convergent or divergent. If it is convergent, find its sum.

Homework Equations



\sum_{n=1}^{\infty} \frac{1 + 2^n}{3^n}

The Attempt at a Solution



Hello,

I have tried to find the sum of this series using both the limit and integral tests, but I cannot get the right answer. My answer is 1/3, but the book says it is 5/2. How can I solve this?
 
Last edited:
Physics news on Phys.org
Yae Miteo said:

Homework Statement



Determine whether the series is convergent or divergent. If it is convergent, find its sum.

Homework Equations



\sum_{n=1}^{\infty} \frac{1 + 2^n}{3^n}

The Attempt at a Solution



Hello,

I have tried to find the sum of this series using both the limit and integral tests, but I cannot get the right answer. My answer is 1/3, but the book says it is 5/2. How can I solve this?

## \sum_{n=1}^{\infty} \frac{1 + 2^n}{3^n} ##
## = \sum_{n=1}^{\infty} \frac{1}{3^n} + \sum_{n=1}^{\infty} \frac{2^n}{3^n} ##

Can you see the solution now?
 
  • Like
Likes 1 person
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...

Similar threads

Back
Top