Question

Where does the second derivative of (x^2)/[(x^2)+3] = 0?

Answer 1

Using the quotient rule, which you should know we get that....
The first derivative of that is:
\[\frac{ 6x }{(3+x^2)^2 }\]
The derivative of that is:
\[\frac{-(18(-1+x^2)) }{ (3+x^2)^3 }\]
Once we simplify the above fraction which you should be able to do we get:
\[x^2-1=0\]
Which is at x=1 and x=-1.
Make sense?

Answer 2

Ah yes, I was making a stupid sign mistake that I did not catch until I saw your second derivative. Thank you!