# Integral

• Mar 9th 2010, 01:14 PM
larryboi7
Integral
$\displaystyle \int_{-\infty}^{\infty} \frac{dx}{x^2(1+e^x)}$

$\displaystyle \int_{1}^{\infty} \frac{e^-x}{\sqrt{x}}dt$

i can't find the anti-derivative of these
• Mar 9th 2010, 06:01 PM
TKHunny
1) Assuming they converge, the definite integral has a specific value. Call the value "A". The subsequent anti-derivative, then, would be Ax + C.

2) Can you prove that they converge? I'm worried about that first one around x = 0.

3) That last one is kind of an Error Function, isn't it? Maybe its complement?

4) What is your assignment and why do you believe either anti-derivative can be determined?
• Mar 9th 2010, 06:22 PM
larryboi7
Quote:

Originally Posted by TKHunny
1) Assuming they converge, the definite integral has a specific value. Call the value "A". The subsequent anti-derivative, then, would be Ax + C.

2) Can you prove that they converge? I'm worried about that first one around x = 0.

3) That last one is kind of an Error Function, isn't it? Maybe its complement?

4) What is your assignment and why do you believe either anti-derivative can be determined?

I have to find out if they converge or diverge.
• Mar 9th 2010, 10:26 PM
Pulock2009
Quote:

Originally Posted by larryboi7
I have to find out if they converge or diverge.

the first one is divergent.

the second one seems to be reducible to some form of the gamma function.