Posted by **KIKSY** on Thursday, March 10, 2011 at 9:05pm.

Thank you for answering the question before bobpursley,

I understand how you did the deriv of inside, outside, but how do I now do the second derivative since you have the extra -18x^2 in the numerator??

Thank you very much! (I suppose I have to brush up on my derivatives)

Posted by KIKSY on Thursday, March 10, 2011 at 8:52pm.

What is the first and second derivative of 3/(1+2(x^3)) ?

im tempted to do the quotient rule, but this looks weird to me...any advice would be greatly appreciated!!

Math - bobpursley, Thursday, March 10, 2011 at 8:55pm

let u=(1+2x^3)

then f= 3u^-1

f'= -3 *u^-2 *u'

but u'= 6x^2

so f'= -3*6x^2 /(1+2x^3)^2

- Math CONTINUATION OF QUESTION FROM bobpursley -
**Reiny**, Thursday, March 10, 2011 at 11:02pm
I don't think bobpursley is on line, so permit me to continue ...

from Bob, y' = -18x^2(1+2x^3)-2

so using the product rule and chain rule combination

y'' = -18x^2)(-2)(1+2x^3)^-3(6x^2) + (1+2x^2)^-2(-36x)

= 216x^4(1+2x^3)^-3 - 36x(1+2x^3)^-2

= 36x(1+2x^3)^-3 [ 6x^3 - (1+2x^3)]

= 36x(1+2x^3)^-3 (4x^3-1)

or

= 36x(4x^3-1)/(1+2x^3)^3

## Answer this Question

## Related Questions

- Pre-cal - Hi, I don't understand this problem also. Find the the relative ...
- Physics, still don't get it! - I'm sorry bobpursley I don't understand your ...
- Reiny or Damon or Bobpursley - Express the series 11 + 18 + 27 +...+ 171 using ...
- chemistry-mostly for bobpursley- I have a question - ok i made a post with this ...
- Calculus--> bobpursley - How do you get m=0? from taking the second ...
- AP calculus BC - hello i know that deriv(cscx) = -cscxcotx and that deriv(cos...
- To:: bobpursley - sorry but i just had one question to my previous question. ...
- To Devron - Since you are a biochemist please look at the post below by C. I ...
- Science-bobpursley - Thanks for helping me with al those parts bobpursley. If ...
- Thanks BobPursley! - Thank you so much for all of your help! I understand now...