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0 votes
0 answers
28 views

Bounding an exponential row

Let $0<c<1$. I need to bound $$ \sum_{i=1}^n \frac{c^{n-i}}{i}\leq C n^{-?} $$ for some constant $C>0$. Does anyone know how to optimal bound this sum? Thank you very much for any suggestions....
emily20's user avatar
  • 155
1 vote
1 answer
78 views

Evaluate $\int \int \int_B x^2+y^2 \, dxdydz$

I'd like to evaluate $\int \int \int_B x^2+y^2 \, dxdydz$ where $B$ is the area enclosed by $x^2+y^2=2z$ and $z=2$ but I'm not sure about the bounds. I've thought something like this... $$\int_0^2 \...
Quotenbanane's user avatar
  • 1,604
3 votes
3 answers
889 views

$\iiint_M (x+y+z)\,dx\,dy\,dz$ over $M=\{(x,y,z)\in\mathbb{R^3}: 0≤z≤(x^2+y^2)^2≤81\}$

$$\iiint_M (x+y+z)\,dx\,dy\,dz$$ over $M=\{(x,y,z)\in\mathbb{R^3}: 0≤z≤(x^2+y^2)^2≤81\}$. How would I express this with the correct bounds? Once I have the bounds I can continue on my own but I need ...
Acyex's user avatar
  • 487
0 votes
0 answers
45 views

Conditions on a rate of change of a continuous function to be bounded

Suppose $f(s)$ is continuous on $[0,\infty)$ and $\lim_{s\to \infty} f(s) =1$. How fast should it decrease to $1$ so that $$F(t)=\int_0^t f(s)\sin(s)ds$$ to be bounded? In what cases it is ...
Andrey Kuzmin's user avatar
0 votes
2 answers
149 views

Does the existence of the integral $\int_0^\infty f(x)dx$ imply that f(x) is bounded on $[0,\infty)$ when f(x) is continuous in this same interval?

Does the existence of the integral $\int_0^\infty f(x)dx$ imply that f(x) is bounded on $[0,\infty)$ when f(x) is continuous in this same interval ? edit I'm trying to use Cauchy without knowing ...
Jewgah's user avatar
  • 29
0 votes
1 answer
65 views

Differentiation Under the Integral Sign w Variable Substitution

Let $f\in C^1(B_\rho(\xi))$, $\xi\in\mathbb{R}^n$ and $\rho>0$. I wish to show $$ \frac{d}{d\rho} \int_{B_\rho(\xi)} f(x)\ dx = \frac{1}{\rho} \int_{B_\rho(\xi)} nf(x) + x\cdot Df(x)\ dx $$ I'm ...
user avatar
1 vote
1 answer
63 views

A confusion about find the boundary of a set $E = D \times E_x$, where $D \subseteq \mathbb{R}^n $ and $E \subseteq \mathbb{R}^1 $

In the book of Mathematical Analysis II by Zorich, at page 132, it is given that However, in the proof of the Remark, I couldn't understand how does the author conclude that $\partial E$ is the ...
Our's user avatar
  • 7,337