Question

which of these relations is a function?

Explanation:

Step1: Recall vertical line test rule

A relation is a function if no vertical line intersects its graph more than once.

Step2: Test top-left ellipse

A vertical line will cross the ellipse at 2 points, so it fails the test.

Step3: Test top-right circle

A vertical line will cross the circle at 2 points, so it fails the test.

Step4: Test bottom-left curve

A vertical line will cross the curve at 2 points, so it fails the test.

Step5: Test bottom-right parabola

Any vertical line will cross the parabola at only 1 point, so it passes the test.

Answer:

The relation represented by the bottom-right upward-opening parabola is a function.