1
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Like, how do you do that as...

2
00:00:06;00 --> 00:00:11;02
If there's positives and no negatives for that part

3
00:00:12;09 --> 00:00:13;12
What do you mean "for that part"?

4
00:00:13;12 --> 00:00:18;05
Like, how would you know to not cross over to the negative?

5
00:00:18;06 --> 00:00:22;13
Oh, you mean, you were one of the ones that got caught into the assumption to
cross right through it?

6
00:00:22;14 --> 00:00:33;02
Ok, so, Danielle, did you first look at positive two as one of your zeros?
So, like, did you have this zero plotted at two?

7
00:00:33;03 --> 00:00:34;03
Yeah

8
00:00:34;03 --> 00:00:37;01
You did? So then it's just the issue of what happened on either side?

9
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Yeah

10
00:00:37;03 --> 00:00:43;05
Ok, so that's actually a good question, because like I said, some of you fell into the
trap and just crossed right through that

11
00:00:43;06 --> 00:00:50;06
And others of you noticed, so that's a great question, I'll turn it over to you guys,
especially maybe those who already caught it

12
00:00:50;07 --> 00:00:59;02
Who didn't get stuck in the trap, who saw it on their own or figured it out on their
own that it is positive before two, then it's zero, then it's positive again.

13
00:00:59;03 --> 00:01:02;08
How do you know that? How can you figure that out?

14
00:01:06;11 --> 00:01:07;09
Julie?

15
00:01:07;10 --> 00:01:12;11
If you take three and plug it in for X

16
00:01:13;10 --> 00:01:19;01
So pick a number over here, for instance three, OK, and what about it?

17
00:01:19;02 --> 00:01:28;01
Plug in three minus two, find out if it's positive or negative, and you do that for each
of them

18
00:01:34;00 --> 00:01:39;12
OK, yeah, so, Danielle, you have to know what's going on on either side of this
zero.

20
00:01:39;13 --> 00:01:47;03
You know that it's a zero and you probably used your function definition to help you
figure that out, but you still have to know what's happening on either end.

21
00:01:47;03 --> 00:01:52;02
So, if you pick a number over here, you already did it and you saw that it was
positive?

22
00:01:53;09 --> 00:01:54;14
Uh yeah

23
00:01:54;15 --> 00:02:02;13
So you pick a number over here and do the same thing, for instance three. You
know, if I plug a three in, what's three minus two? Is it a positive or a negative?

24
00:02:02;13 --> 00:02:03;09
Positive

25
00:02:05:00 --> 00:02:06;12
So, three minus two again.

26
00:02:06;13 --> 00:02:08;12
Uh, positive

27
00:02:09;10 --> 00:02:11;12
Three minus five

28
00:02:12;09 --> 00:02:13;06
Negative

29
00:02:14;08 --> 00:02:15;14
Three minus seven

30
00:02:15;15 --> 00:02:16;09
Negative

31
00:02:17;00 --> 00:02:20;11
K, so negative times a negative

32
00:02:20;12 --> 00:02:21;10
Positive

33
00:02:22;08 --> 00:02:28;04
So, positive times positive times positive. I don't know what number it is, but what's
the sign of this product?

34
00:02:28;04 --> 00:02:28;13
Positive

35
00:02:28;13 --> 00:02:35;12
Positive. That's why it is positive still. So, that's a really good question.
Does that answer it for you?

36
00:02:35;13 --> 00:02:36;06
Yeah

37
00:02:36;07 --> 00:02:46;07
K, so you guys, that's just it. You don't want to fall into this trap of saying "OK, well,
here's root" or, I'm sorry, "here's a spot where it's zero",

38
00:02:46;08 --> 00:02:54;06
"I'm just gonna cross right through it and go find my next zero". Because what if it doesn't cross right through it? What if it does something like this?

39
00:02:54;07 --> 00:03:05;00
K, so that's why you had to pick values on either side and actually go see is it positive, is it negative