Answer:
(-∞,-2)
Explanation:
See the graph attached to this question.
The value of f(x) is constant for the part of the graph which is at the leftmost.
The values of x for which the function f(x) is constant that we have to determine.
From the graph, it is clear that for x < 2 ( but not including 2) the function is constant.
Therefore, the required interval of x is (-∞,-2) (Answer)