Return to Video

Inequalities on a number line

  • 0:01 - 0:04
    Graph x is less than 4.
  • 0:04 - 0:07
    So let's draw ourselves
    a number line over here.
  • 0:07 - 0:10
    So let me draw a number line.
  • 0:13 - 0:20
    I'll start here at 0,
    so 0, 1, 2, 3, 4, 5.
  • 0:20 - 0:21
    And we could go below 0.
  • 0:21 - 0:26
    We'd have negative 1, negative
    2, negative 3, negative 4.
  • 0:26 - 0:28
    I could keep going.
  • 0:28 - 0:32
    Now, we want to graph all of
    the x's that are less than 4,
  • 0:32 - 0:33
    but we're not including 4.
  • 0:33 - 0:35
    It's not less than
    or equal to 4.
  • 0:35 - 0:37
    It's just less than 4.
  • 0:37 - 0:40
    And to show that we're not
    going to include 4, what we're
  • 0:40 - 0:43
    going to do is we're going
    to draw a circle around 4.
  • 0:43 - 0:45
    So this shows us that
    we're not including 4.
  • 0:45 - 0:49
    If we were including 4, I
    would make that a solid dot.
  • 0:49 - 0:53
    And to show that we're going to
    do all the values less than 4,
  • 0:53 - 0:55
    we want to shade
    in the number line
  • 0:55 - 0:59
    below 4, going down
    from 4, just like that.
  • 1:02 - 1:06
    And then we can just shade
    in the arrow just like that.
  • 1:06 - 1:10
    So this right here is all
    of the values less than 4.
  • 1:10 - 1:11
    And you could test it out.
  • 1:11 - 1:13
    Take any value
    where there's blue.
  • 1:13 - 1:16
    So there's blue over
    here, negative 2.
  • 1:16 - 1:21
    Negative 2 is
    definitely less than 4.
  • 1:21 - 1:23
    If you take this value
    right here, this 2,
  • 1:23 - 1:25
    it's definitely less than 4.
  • 1:25 - 1:28
    4 is not included because
    4 is not less than 4.
  • 1:28 - 1:29
    It's equal to 4.
  • 1:29 - 1:33
    5 is not included because
    5 is not less than 4.
Title:
Inequalities on a number line
Description:

more » « less
Video Language:
English
Team:
Khan Academy
Duration:
01:34

English subtitles

Revisions Compare revisions