The graph provided shows a downward-opening parabola, which is characteristic of a quadratic function of the form $f(x) = ax^2 + bx + c$, where $a < 0$.

To determine where the function is increasing, we need to analyze the slope of the curve. A function is increasing on an interval where its derivative is positive (i.e., the slope of the tangent line is positive).

From the graph, the vertex of the parabola occurs at $x = 0$, which is the maximum point. The function increases on the left of the vertex, where the curve rises.

Conclusion: The function is increasing on the domain $(-\infty, 0)$, as the curve rises from negative infinity until it reaches the peak at $x = 0$.

Would you like further details on how to find the vertex or analyze the behavior of this quadratic function?

Here are 5 related questions:

1. How can you determine the domain of a quadratic function?
2. What is the significance of the vertex in a parabola?
3. How do you calculate the derivative of a quadratic function?
4. What does it mean for a function to be increasing or decreasing?
5. Can a quadratic function be increasing and decreasing at the same time?

Tip: The vertex of a parabola given by $f(x) = ax^2 + bx + c$ is located at $x = -\frac{b}{2a}$, which helps identify intervals where the function increases or decreases.