Q: Find where f(x) = x³ − 3x is increasing/decreasing. f'(x) = 3x² − 3 = 3(x−1)(x+1). Critical: x = ±1. Intervals: (−∞,−1): f' > 0 increasing; (−1,1): f' < 0 decreasing; (1,∞): f' > 0 increasing.