I need help with this quick question. PLS

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  x < -5

Step-by-step explanation:

The function is increasing where its slope is positive. That is where each point is higher than the one to its left. You see that is the case for all points to the left of the vertex, which is at x=-5.

The domain where the function is increasing is x < -5.

Additional comment

At the vertex, the function is horizontal, neither increasing nor decreasing. So, the vertex itself is not included in the domains of increase or decrease.