A vertex is where a parabola turns; if it opens upward, that point is its lowest spot. When the graph already shows that spot, read it directly instead of redrawing it in Desmos. Then check which coordinate the question asks for: the first number gives horizontal position, and the second gives height. A nearby marked point may not be the vertex.
Hints
- Hint 1
The vertex is where a parabola changes direction. An upward-opening parabola turns at its lowest point, so look for the dot at the bottom rather than the dots farther up.
- Hint 2
A point is written : its first number gives its horizontal position, and its second gives its height. Once you find the vertex, which number answers a question about its -coordinate?
Step-by-step
Read the vertex from the graph
Step 1Find the turning point
No Desmos needed. The graph already marks the turning point. An upward-opening parabola turns at its vertex, so the vertex is its lowest point. The solid dot at is lower than the dots at and .
- Step 2
Read the requested coordinate
An ordered pair lists horizontal position first and height second. Take the coordinate the question names. The vertex has -coordinate ; is its height. Choice C.