ACT Preparation / Unit 9 ACT 0812 short lesson, about 20 seconds
Horizontal and Vertical Lines
Captions available
The idea
A horizontal line, y = c, has slope 0. A vertical line, x = c, has an undefined slope, because its run is zero.
In practice
Through (2, −5): the horizontal line is y = −5; the vertical line is x = 2.
Where people slip
Zero slope and undefined slope are different: 0/4 is 0, but 4/0 is undefined.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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