Question

How do you use the 2nd derivative test to find all relative extrema of `f(x)=(9x^(2)+1)/x`?

Answer 1

Have a look:

The change of concavity occurs at `x=0` which is not a point accepted by our function.
graph{(9x^2+1)/x [-41.1, 41.12, -20.54, 20.54]}