A maximum value is a function’s greatest output, so on a graph you’re looking for the highest -coordinate. For a downward-opening parabola, that height is at the vertex, the point where the curve turns. If the point is labeled, read it directly rather than redrawing the graph in Desmos. Don’t confuse the height with the input where it occurs.
Hints
- Hint 1
A downward-opening parabola reaches its greatest height at its vertex, the point where the curve turns from rising to falling. Which labeled point is at that turn?
- Hint 2
At a graph point , is the input and is the output. A maximum value asks for the greatest output. Which coordinate of the highest point gives you that?
Step-by-step
Read the highest point
Step 1Locate the maximum
No Desmos needed. The graph already labels the highest point. Since the parabola opens downward, its vertex, the point where it turns, is its highest point. The maximum value of is the height of that point.
- Step 2
Read the height
The labeled vertex is , so : input gives output . The maximum value is the -coordinate, not the input where it happens. The maximum value of is . Choice B.