The words crosses the -axis point to x-intercepts, where the graph has height . Read the horizontal coordinate of each marked crossing and add those numbers with their signs. A given graph makes Desmos unnecessary. Don't use the vertex's horizontal coordinate as the sum: on a parabola, it's the midpoint of the crossings.
Hints
- Hint 1
An x-intercept is where the graph meets the horizontal axis, so its vertical coordinate is . In and , which coordinates do and stand for?
- Hint 2
Each marked point is an ordered pair: its first number is its horizontal coordinate. Read the first number at each crossing, keeping the negative sign on the point left of the vertical axis.
Step-by-step
Read and add the intercepts' x-coordinates
Step 1Identify what and mean
No Desmos needed. Both crossings are already marked on the graph. An x-intercept is a point where the graph meets the horizontal -axis. In and , and are the horizontal coordinates, not the heights.
- Step 2
Read the two marked points
The graph crosses at and . Read the first coordinate of each point, so and , or the reverse. Keep the minus sign on the crossing left of the vertical axis.
- Step 3
Add the signed coordinates
Add the two -coordinates:
The sum of the intercepts' -coordinates is . Choice C.