9: The domain is D( f ) = ℝ.
The derivative is

Critical points: The equation f ′(x) = 0 has solutions x = −1 and x = 1.
There are no points in D( f ) where the derivative does not exist.

Intervals of monotonicity will be (−∞,−1], [−1,1], and [1,∞). Determine monotonicity and local extrema using a chart.

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