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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
1 vote
1 answer
197 views

Limit of ratio of incomplete gamma function

In order to derive Sterling's approximation, I need to show that the following integral decays quicker than at least $\mathcal{O}(n^2)$: $\lim_{n\to\infty}\dfrac{\int_{2n}^\infty x^ne^{-x}dx}{\int_{0}^...
Kutsit's user avatar
  • 185
0 votes
1 answer
33 views

Limits of bounded region

While solving a simple problem for finding are of the region bounded by $x=y^2$ and $x=y$. Are the following correct limits? When $x$ is the outer integration variable $$\int^1_0\int^\sqrt{x}_xdydx$$...
SJa's user avatar
  • 849
2 votes
3 answers
139 views

Evaluating $\int_{-\infty}^\infty 1-e^{-\frac{1}{x^2}}{\rm d}x$

I am interested in the improper integral: $$I=\int_{-\infty}^\infty 1-e^{-\frac{1}{x^2}}{\rm d}x=2\int_{0}^\infty 1-e^{-\frac{1}{x^2}}{\rm d}x$$ which I am fairly sure converges. I broke the integral ...
aleden's user avatar
  • 4,027