Consider the function below f(x) = x3 − 12x + 3 find intervals of increase and decrease

Turning points are where the derivative is zero.
  f'(x) = 0 = 3x² -12
  0 = 3(x -2)(x +2)
The values of x that satisfy this are x=2, x=-2.

Since the coefficient of x³ is positive, we know the function is generally increasing left-to-right. It will have an interval of decrease between the turning points.

  increasing: (-∞, -2) ∪ (2, ∞)
  decreasing: (-2, 2)

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