So for the function (x^3 + 2)/(x^4 + 1) I needed to find the values where it is increasing and decreasing. I used
Reduce[D[f[x], x] > 0, x] // N
to find where it is increasing. Then I used
Reduce[D[f[x], x] < 0, x] // N
to find where it is decreasing. When I run that code I get
-2.11198 < x < 0. || 0. < x < 0.372591
and
x < -2.11198 || x > 0.372591
So my question is how do I turn those answers into coordinate pairs? To look like this: (-2.111985,0)∪(0,0.372591) and (-∞,-2.111985)∪(0.372691,∞)