College Algebra / Unit 5 Alg 242 short lesson, about 20 seconds
The Vertical Line Test
Captions available
The idea
The vertical line test reads a graph: if any vertical line crosses the graph more than once, the graph is not a function.
In practice
The graph of x = y² contains (4, 2) and (4, −2); the vertical line x = 4 hits both, so one input claims two outputs.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
- Nothing. This is a starting point.
Unlocks
- Nothing yet depends on this.
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