Question

1. which graph is an example of a function?

a
graph of a parabola opening upwards

b
graph of an ellipse

c
graph of a sideways parabola

d
graph of a circle

Explanation:

To determine which graph is a function, we use the vertical line test: a graph represents a function if no vertical line intersects it more than once.

• For Option A (the parabola opening upwards), any vertical line will intersect the graph at most once.
• For Option B (the ellipse), a vertical line through the ellipse will intersect it twice.
• For Option C (the sideways parabola), a vertical line will intersect it twice.
• For Option D (the circle), a vertical line through the circle will intersect it twice.

Thus, only Option A passes the vertical line test.

Answer:

A. The graph of the upward - opening parabola