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### Course: 7th grade (Illustrative Mathematics)>Unit 5

Lesson 3: Lesson 3: Changing elevation

# Number equations & number lines

Integer equations to describe diagram.

## Want to join the conversation?

• why do you put ( ) on a negative number
(20 votes)
• it helps you know wether or not it is a negative number.
(18 votes)
• Bruh, my mom said that to get screen time I have to study for 120 minutes, I'm just watching this video to make time pass.
(26 votes)
• I feel bad
(2 votes)
• What is this comment section?
(20 votes)
• if you really want weird comments look at the comments for last video Q.nomorereadingininginmathpls's post hello cha t how is your day?
(3 votes)
• I'm looking at this vidio for energy points(no jokes), because it is to easy
(14 votes)
• ``if (x < 0) {    return;}``
(11 votes)
• why are negative numbers in brackets? For example, 14 + (-12)=
(5 votes)
• To help tell that it is a negative number. In simpler form to separate it ,which makes it easier to tell the difference. For example let’s say I got this .
6- - 8
It is a bit harder to tell the difference. So now let me put it in parentheses.
6-(-8)
It separates the negative 8 from the negative sign making it easier to tell, but you don’t HAVE to put it. It just makes it easier to solve. Hope this helps!
(6 votes)
• this is so easy :]
(6 votes)
• this video actualy makes sense
(6 votes)
• yes i agree with you
(1 vote)
• this is so easy I could have graduated collage!
(5 votes)
• this is so easy I could have graduated collage!
(2 votes)
• Å̵̺̯̲̞̺̏͐̾̚H̶̢̺͔̼̞͒̃̅͂̇H̷̨̭͍͖̹̓̏̀̏͝H̵̢͈̮͎͚́͐̓͒̋H̷̬̺̪̙̗̃̒̏̉̉Ȟ̷̥̣̯̘̻̂̍̍̆ while the apple is strange is is special in its own way
(5 votes)

## Video transcript

- [Voiceover] We're told to fill in the blanks to complete the equation that describes the diagram. So let's think about what's going on over here. If we start at zero, and we move one, two, three, four spaces to the right of zero, this arrow right over here represents positive four. We already see that right over here in the equation. Then from positive four, from the tip of this arrow, we then go one, two, three, four, five, six spaces to the left. So what we just did here is we just added a negative six to the positive four. Positive four plus negative six. Where does that put us? Well we see it puts us one, two spaces to the left of zero and each of these spaces in this diagram are one. So two spaces to the left of zero is going to be negative two. This is fun. Let's keep doing more examples. Write an addition equation or a subtraction equation, your choice, so they're giving us some choice, to describe the diagram. Alright, let's see what's going on here. We're starting at zero and we're going one, two, three, four to the left. So if we're going four to the left or so we can say negative four, -4. And then we're going to go another one, two, three, four, five, six, seven, eight, nine to the left. So we could write this as negative four minus nine is equal to. And when you go four to the left and then you go another nine to the left, you end up 13 to the left of zero which is negative 13. Equals negative 13. So this way I've written it as a subtraction equation I guess you could say. Negative four minus nine, is equal to negative 13. Now another way I could have done it, I could have said negative four plus negative nine is equal to negative thirteen as well. Either of those would have been legitimate. Now I've written it as an addition equation. Let's keep going. Fill in the blanks to complete the equation that describes the diagram. So we're starting at zero, we go three to the left of zero, that's negative three. Then we go another three to the left of that. So we're going to add another negative three. We're going to add another negative three and that puts us six to the left of zero. Well six to the left of zero is negative six. And we're done.