Question

1. which of the following graphs represents a function?

a. a parabola opening sideways
b. a parabola opening upwards
c. a circle
d. an ellipse

Explanation:

To determine if a graph represents a function, use the Vertical Line Test: any vertical line drawn on the graph should intersect it at most once.

• A sideways parabola fails: a vertical line intersects it twice.
• An upward-opening parabola passes: every vertical line intersects it at most once.
• A circle fails: most vertical lines intersect it twice.
• An ellipse fails: most vertical lines intersect it twice.

Answer:

b. A parabola opening upwards