Evaluating improper integrals with characteristics of both type I and type II

923 Views Asked by At

Integrating improper integrals constitute of integrating functions

1) over an infinite integral

2) over an interval where f has a discontinuity.

Namely, integrals type I and type II, respectively. Generally, both types are solved in the same way using limits.

But consider the following integral:

$\int_0^\infty \frac{1}{\sqrt[3]{x}} dx$

In this case, I would proceed to set the integral $\int_0^t \frac{1}{\sqrt[3]{x}} dx$ to $\displaystyle\lim_{t\to \infty}$. However, $\frac{1}{\sqrt[3]{x}}$ is discontinuous at $x=0$.

Why is this disregarded during integration??

1

There are 1 best solutions below

2
On BEST ANSWER

i think in that case you divide the integral in two because it have two cases of improper integral, so you make

$$\int_{0}^{+\infty}\frac{dx}{\sqrt[3]{x}}=\int_{0}^{1}\frac{dx}{\sqrt[3]{x}}+\int_{1}^{+\infty}\frac{dx}{\sqrt[3]{x}}$$ so you study both part separated and in order to the original integral converge both integrals should converge. so it will be something like

$$\int_{0}^{1}\frac{dx}{\sqrt[3]{x}}=\lim_{t\to0^+}\int_{t}^{1}\frac{dx}{\sqrt[3]{x}}$$

and

$$\int_{1}^{\infty}\frac{dx}{\sqrt[3]{x}}=\lim_{t\to\infty}\int_{1}^{t}\frac{dx}{\sqrt[3]{x}}$$