# Math Help - I've got no idea where to start. Integration with negative powers.

1. ## I've got no idea where to start. Integration with negative powers.

integrate (1/(sqrt x)) (e^-x) dx

I tried integrating by parts but it doesn't work. Please help!

2. ## Re: I've got no idea where to start. Integration with negative powers.

Originally Posted by jameshow
integrate (1/(sqrt x)) (e^-x) dx
I tried integrating by parts but it doesn't work. Please help!
There is no elementary anti-derivative for that. See here.

3. ## Re: I've got no idea where to start. Integration with negative powers.

Originally Posted by Plato
There is no elementary anti-derivative for that. See here.
So what should I do?

4. ## Re: I've got no idea where to start. Integration with negative powers.

Originally Posted by jameshow
So what should I do?
This depends on why you are trying to solve this problem. The answer may range from ignoring the problem to learning about the error function. In between are options to compute this integral numerically and contact your instructor to double-check the problem statement. For example, it may be that this integral is supposed to be from 0 to ∞.

5. ## Re: I've got no idea where to start. Integration with negative powers.

Originally Posted by emakarov
This depends on why you are trying to solve this problem. The answer may range from ignoring the problem to learning about the error function. In between are options to compute this integral numerically and contact your instructor to double-check the problem statement. For example, it may be that this integral is supposed to be from 0 to ∞.
The limits are from 0 to 0.25.

Here's the question:
You are tasked to write a computer program to compute the value of integrate (1/(sqrt x)) (e^-x) dx from 0 to a. Where the value a is determined at runtime.

i) Estimate the value of integrate (1/(sqrt x)) (e^-x) dx from 0 to 0.25 (directly).
ii)List the steps to implement the method used in the above question to compute integrate (1/(sqrt x)) (e^-x) dx from 0 to a in your program. In your implementations, do not cater to the fact that the value of a is determined at run time. The detail of the coding is not required.

Sorry for the trouble and thanks!

6. ## Re: I've got no idea where to start. Integration with negative powers.

Originally Posted by jameshow
You are tasked to write a computer program to compute the value of ...
In that case you need to use numerical method.. Numerical integration - Wikipedia, the free encyclopedia