Determine the interval(s) where the function f(x)=x3−3xf(x) = x^3 - 3xf(x)=x3−3x is strictly increasing.
(−∞,−1)(-\infty, -1)(−∞,−1)
(−1,1)(-1, 1)(−1,1)
(1,∞)(1, \infty)(1,∞)
(−∞,−1)∪(1,∞)(-\infty, -1) \cup (1, \infty)(−∞,−1)∪(1,∞)