WEBVTT
1
00:00:00.340 --> 00:00:02.529 A:middle L:90%
So in this example, we're going to graft the
2
00:00:02.529 --> 00:00:05.429 A:middle L:90%
equation. Four X minus five y is equal to
3
00:00:05.429 --> 00:00:08.480 A:middle L:90%
20. Well, this equation is in standard form
4
00:00:08.490 --> 00:00:11.970 A:middle L:90%
because it's in the form a X plus B y
5
00:00:12.439 --> 00:00:14.849 A:middle L:90%
equals C, where a, B and C are
6
00:00:14.849 --> 00:00:17.949 A:middle L:90%
just Constance. So remember when we graph equations in
7
00:00:17.949 --> 00:00:20.250 A:middle L:90%
standard form, what we need to do first is
8
00:00:20.250 --> 00:00:22.570 A:middle L:90%
find the X and y intercepts. So let's start
9
00:00:22.579 --> 00:00:26.870 A:middle L:90%
by finding the X intercept. So remember, X
10
00:00:26.870 --> 00:00:30.690 A:middle L:90%
intercept is the point on your graph that where crosses
11
00:00:30.690 --> 00:00:33.509 A:middle L:90%
the X axis Well, any point that's on your
12
00:00:33.509 --> 00:00:36.939 A:middle L:90%
X axis has to John Reform X comma zero.
13
00:00:36.960 --> 00:00:39.439 A:middle L:90%
So it's why corn it is always zero, and
14
00:00:39.439 --> 00:00:42.359 A:middle L:90%
the X value just depends on your equation. So
15
00:00:42.359 --> 00:00:44.380 A:middle L:90%
to find your ex intercept, what we're going to
16
00:00:44.380 --> 00:00:47.799 A:middle L:90%
dio is substitute zero in place of why in our
17
00:00:47.799 --> 00:00:49.979 A:middle L:90%
equation, So when we do that, we'll have
18
00:00:49.979 --> 00:00:55.570 A:middle L:90%
four X minus five times zero is equal to 20
19
00:00:56.640 --> 00:00:58.359 A:middle L:90%
. And now we just have to solve this equation
20
00:00:58.359 --> 00:01:00.149 A:middle L:90%
for X Well, negative five times zero is just
21
00:01:00.149 --> 00:01:03.659 A:middle L:90%
zero. So this park cancels so we're left with
22
00:01:03.659 --> 00:01:06.420 A:middle L:90%
four X is equal to 20. So the solve
23
00:01:06.420 --> 00:01:07.189 A:middle L:90%
for X we're going to divide both sides of our
24
00:01:07.189 --> 00:01:11.079 A:middle L:90%
equation by four and 20. Divided by four is
25
00:01:11.079 --> 00:01:14.890 A:middle L:90%
five. That means our X intercept will take on
26
00:01:14.890 --> 00:01:18.489 A:middle L:90%
the form 50 So let's go ahead and plot that
27
00:01:18.489 --> 00:01:19.750 A:middle L:90%
point so we'll go to the right five and plot
28
00:01:19.750 --> 00:01:22.969 A:middle L:90%
it. So this is one point on our graph
29
00:01:23.939 --> 00:01:25.819 A:middle L:90%
. Well, now that we know the x intercept
30
00:01:25.829 --> 00:01:26.959 A:middle L:90%
, we're gonna go ahead and find the Y intercept
31
00:01:27.439 --> 00:01:30.219 A:middle L:90%
. I remember the Y intercept tells us the point
32
00:01:30.219 --> 00:01:33.500 A:middle L:90%
on our line that it hits the oh, the
33
00:01:33.500 --> 00:01:36.840 A:middle L:90%
Y axis. Now, for any point that falls
34
00:01:36.840 --> 00:01:38.849 A:middle L:90%
on our Y axis is going to take on the
35
00:01:38.849 --> 00:01:42.310 A:middle L:90%
general form zero comma y. So the X coordinate
36
00:01:42.319 --> 00:01:44.670 A:middle L:90%
is always zero and the white corn, it varies
37
00:01:44.670 --> 00:01:47.560 A:middle L:90%
from equation to equation. So the salt for our
38
00:01:47.560 --> 00:01:49.329 A:middle L:90%
Y intercept, we're going to substitute zero and place
39
00:01:49.329 --> 00:01:52.890 A:middle L:90%
of acts in our original equation. So we're gonna
40
00:01:52.890 --> 00:01:57.939 A:middle L:90%
have four times zero minus five. Y is equal
41
00:01:57.939 --> 00:02:00.459 A:middle L:90%
to 20 and then we just solve the equation for
42
00:02:00.459 --> 00:02:01.829 A:middle L:90%
why? Well, four times zero is zero.
43
00:02:01.909 --> 00:02:05.200 A:middle L:90%
So this park cancels, so we're just left with
44
00:02:05.200 --> 00:02:08.120 A:middle L:90%
negative five y is equal to 20. So the
45
00:02:08.120 --> 00:02:10.219 A:middle L:90%
salt for why we're gonna divide both sides of our
46
00:02:10.219 --> 00:02:14.460 A:middle L:90%
equation by negative five and 20. Divided by negative
47
00:02:14.460 --> 00:02:16.349 A:middle L:90%
five is negative. Four. So our why intercept
48
00:02:16.349 --> 00:02:20.340 A:middle L:90%
is negative for so in terms of an ordered pair
49
00:02:20.349 --> 00:02:22.550 A:middle L:90%
, the ordered pair would be zero negative four.
50
00:02:23.539 --> 00:02:24.139 A:middle L:90%
And now that we know our y intercept, we
51
00:02:24.139 --> 00:02:25.990 A:middle L:90%
can go ahead and plot it. So the plot
52
00:02:25.990 --> 00:02:30.930 A:middle L:90%
this point, we simply go down. For now
53
00:02:30.930 --> 00:02:32.099 A:middle L:90%
that we know two points on our line, we
54
00:02:32.099 --> 00:02:35.340 A:middle L:90%
just now need to draw the line that connects T
55
00:02:35.349 --> 00:02:37.539 A:middle L:90%
, connects them and make sure you go all the
56
00:02:37.539 --> 00:02:38.439 A:middle L:90%
way through. Because, remember, a line goes
57
00:02:38.439 --> 00:02:43.469 A:middle L:90%
on infinitely in both directions. So now we have
58
00:02:43.469 --> 00:02:46.819 A:middle L:90%
graft the equation. Four x minus five y equals
59
00:02:46.819 --> A:middle L:90%
20.