To determine the range of values where the function $y = f(x)$ is positive, we need to identify the intervals on the x-axis where the graph of the function is above the x-axis (i.e., where $y > 0$).

Upon examining the graph:

• The function $f(x)$ is positive between the points where the graph crosses the x-axis.
• The graph crosses the x-axis at $x = 4$ and $x = 11$.

Therefore, the function is positive between $x = 4$ and $x = 11$.

Answer:

The function $y = f(x)$ is positive in the range $(4;11)$.

Do you want details or have any questions?

Here are 5 related questions:

1. How would the answer change if the graph crossed the x-axis at more points?
2. What would the range be if the function was negative instead of positive?
3. Can you identify any local maxima or minima on the graph?
4. How do you determine the exact points where the graph intersects the x-axis?
5. What is the significance of the points where the function crosses the x-axis?

Tip: When analyzing the positivity of a function, focus on where the graph is above the x-axis.