Answer
$(-1,1)$
Work Step by Step
A curve is concave up if its slope is increasing, in which case the second derivative is positive.
A curve is concave down if its slope is decreasing, in which case the second derivative is negative.
A point in the domain of $f$ where the graph of $f$ changes concavity, from concave up to concave down or vice versa, is called a point of inflection.
At a point of inflection, the second derivative is either zero or undefined.
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Observing from left to right,
$(-\infty,-2)\quad$ slope positive, decreasing (concave down)
$ x=-2\quad$ local maximum, slope becoming negative, (decreasing: concave down)
$(-2,-1)\quad$ slope negative, decreasing (still concave down)
$ x=-1\quad$ slope negative, but becoming less negative, increases, (change of concavity)
$(-1,0)\quad$ slope negative, increasing to zero (concave up)
$x=0\quad$ local minimum, slope becoming positive (still increasing, concave up)
$(0,+\infty)\quad$ slope positive, continues increasing, (concave up).
Change of concavity at $x=-1$.
Inflection point: $(-1,1)$
