On what intervals is.....

Question

anonymous · Answer

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anonymous · Answer

did you find f''(x) = 0?

anonymous · Answer

no i didn't....

lemme see...

so f'(x) of ln(x^2+1) = 2x 
                              --------
                                  x^2 + 1 

? and f '' (x) would be
   2(x^2-1)
-   ---------
    (x^2+1)^2 
??

ganeshie8 · Answer

f"(x) has to be POSITIVE, for it to be "concave up"

anonymous · Answer

oh:(
darn then i don't know what to do:(

mathmale · Answer

I'm going to take your word for the correctness of the 2nd derivative.
1.  Find the possible point of inflection:  set the 2nd deriv. = to 0.
2.  Find the solution(s)
3.  Graph the sol'ns on a number line
4.  Identify the intervals defined by those sol'ns graphed on the number line.

anonymous · Answer

i'm not quite sure how to do that ^^ 
:(

mathmale · Answer

This is much like the task of finding intervals on which the graph is increasing or decreasing.
Assuming that your second der. is correct, set it = to 0 and find the roots.

anonymous · Answer

could you possibly walk me through it?

anonymous · Answer

^^ the steps that you wrote above?

anonymous · Answer

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