Answer:
(-∞, -3) and (-1, ∞)
Step-by-step explanation:
A function is increasing when the gradient is positive.
A function is decreasing when the gradient is negative.
A function is stationary when the gradient is zero.
From inspection of the given graph, the turning points of the function are (-3, 3) and (-1, -1). Therefore, the gradient is zero at these points.
From inspection of the graph:
- The function is increasing on the interval (-∞, -3).
- The function is stationary at x = -3.
- The function is decreasing on the interval (-3, -1).
- The function is stationary at x = -1.
- The function is increasing on the interval (-1, ∞).
Therefore, the function is increasing on the intervals (-∞, -3) and (-1, ∞).
