# simple integration problem#2

• Jan 23rd 2009, 12:33 AM
slaypullingcat
simple integration problem#2
I'm back, how do I integrate (x^2+2)^2? I need to integrate this to find the volume of a solid. Cheers
• Jan 23rd 2009, 12:54 AM
Moo
Hello,
Quote:

Originally Posted by slaypullingcat
I'm back, how do I integrate (x^2+2)^2? I need to integrate this to find the volume of a solid. Cheers

$(x^2+2)^2=x^4+4x^2+4$

I'm sure you can handle it from here :D
• Jan 23rd 2009, 01:11 AM
slaypullingcat
thanks very much. Out of curiosity, is that the normal method of solving a question like that? Expand it then integrate as usual? What happens with higher powers? Is there a rule I should know about?
• Jan 23rd 2009, 01:23 AM
Moo
Quote:

Originally Posted by slaypullingcat
thanks very much. Out of curiosity, is that the normal method of solving a question like that? Expand it then integrate as usual? What happens with higher powers? Is there a rule I should know about?

Well, with higher powers you can use the binomial theorem, but it's likely not to give you a nice form.

Otherwise, see if you can have something in the form $u'(x) [u(x)]^n$ which has the following antiderivative : $\frac{[u(x)]^{n+1}}{n+1}+C$
• Jan 23rd 2009, 01:38 AM
mr fantastic
Quote:

Originally Posted by slaypullingcat
I'm back, how do I integrate (x^2+2)^2? I need to integrate this to find the volume of a solid.

It probably would be better if you posted the whole question and then showed your working up to this stage (just in case this is the wrong integral).
• Jan 23rd 2009, 02:17 AM
slaypullingcat
Thanks a lot for your help. I appreciate you taking the time. Cheers