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How To Subtract Positive And Negative Integers
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Feb 19, 2025
We're continuing our series with integers and in our last session, we talked about how to add integers. We'll now move on to section 2 and discuss subtracting positive and negative integers. This can be very challenging for some students but we'll try to make it palpable. Chapters: 00:00 Introduction 00:39 Subtracting Integers using the number line 01:55 Real life example 02:30 How To subtract positive integers 04:03 Real life example 04:23 How To subtract negative integers 06:50 practice problems
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0:00
okay so we talking about subtracting
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integers right subtracting
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integers so we just talked about adding
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them and now we're going to talk about
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subtracting the thing is
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this like I said in the last section
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these are key to everything that we
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going to do from here which is equations
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inequalities fractions we're going to
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talk about all of this so we we have to
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like really pay attention and get this
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right so if you don't understand is you
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need to spend time on the weekend
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studying that so now first we're going
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to talk about what it looks like on the
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number line how does I show on the
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number line how do you subtract integers
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using the number line right so if you
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look at my number line here I am trying
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to do 4 - 9 all right that's what I'm
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trying to do 4 - 9 and I need you all to
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take notes because if you don't
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understand it you better take notes or
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you may have to go back and watch watch
1:00
this I'll go back and watch it okay so
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it's up to you so we doing four - 9 so
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if that four is on the right side of
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zero right CU I have 1 2 3 4 I'm here
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right and I want to take away from four
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nine so if I'm
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here and I want to take away 9 from four
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I'm going to
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go 1 2 3 4 5 6 7 8 and nine right four
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from nine and now I land over here I
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land at where -5 because I'm on the left
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side of zero right so 4 - 9 is
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technically saying 4 + -9 which is what
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55 so 4 - 9 is five now the way I
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thought this like for the last couple of
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years is this assume that you have $4 in
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your
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account right assume that you have $4 in
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your account and and then you spend
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$9 now what happens you have negative
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you have negative you owe money you owe
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$5 right so you owe five and when you
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owe is it positive or negative negative
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negative so therefore 4 - 9
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is5 right so you have to be careful with
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that because as we go on it's going to
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get harder right so now we're going to
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learn so the first thing is this we're
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going to learn how to subtract
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positive integers right we're going to
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learn how to subtract positive integers
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okay so I have
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-7 and I'm taking it away from -7 3
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right so -7 is on this side of um zero
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on the left side of zero and I want to
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take away from this three so am I going
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to go right or left left so if I'm here
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I'm going to go 1 2 3 Aline where
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10 -10 so -3 - 7 is -10 this is proba
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probably by far the most confusing out
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of every single one of them a lot of
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people get confused with this right
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because 7 - 3 can also be written as
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what -7 + -3 so if you one of those that
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don't get it if you ever see something
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like this like -2 - 3 just go ahead and
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change it so that we make sense to you
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it's basically saying
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-2 + -3 and that gives you5
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or that's a negative times a negative is
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a positive right but a negative plus a
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negative gives you a negative because
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you suppose you owe seven and then you
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spend another three you're still
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what negative you still in De you still
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have a negative right so a negative plus
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a negative is a negative okay so if you
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owe
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$7 and you spend another $3 now what do
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you have you owe $10 you're still short
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okay so the key is this if you have this
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a succession of negative like that so
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just use the plus sign so it helps you
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okay now the next one is subtracting a
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negative integer now this one is the
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funnest this is this one I like the most
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right because if I have negative 7 - -3
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guess what I do it make it a positive
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I'll make it a positive you see this
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right you see this here you make it a
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positive you have two negatives you
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automatically make it a positive okay 7
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- -3 is 7 + 3 so change it so this is
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what we did last year we I learned from
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Reagan she used to love doing this she
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used to put it like this and turn into a
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positive so that becomes 7 + 3 that
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becomes 10 she love doing it right which
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s
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oh right and then here we have -7 minus
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-3 right same thing yeah if the so if
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the I not so if the negatives are are
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next each other that equals a positive
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that equals a positive so right if the
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negative are next to each other it
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becomes a positive same thing here I
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have -7 - -3 becomes 7 + 3 and that
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equals what4 because you
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ow7 7 and you add $3 add three you still
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owe $4 still owe right and that's a
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negative so now what we're going to do
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is I going to have you guys work on
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several examples to see if you
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understand it okay because we have to do
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that the only way to understand
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something is to work on more
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problems this is how you learn okay so
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let's go ahead and do this here let me
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actually can I eras this yeah right
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so examples we're going to work on some
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examples so let's say we have
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10 -
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[Music]
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19 10 + -19 and then we have uh
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7 -
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20 and then
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-7
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- 10
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[Music]
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and
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12 what
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color all right let's do this what color
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pink all
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right so what do you all think -10 - 19
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is going to be
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20 29 - 29 does anybody understand that
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right -10 - 19 is -29 thank
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you what about -10 + 9 2929 why do you
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think that this both of them at the same
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time because they're both the same right
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I want to show you that this and these
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are the same thing same the same thing
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right we're saying technically the same
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thing when we do this and that I'm
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saying the same thing okay I want you to
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get that now what is 7 - 20 say that
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um
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mhm yeah let's use it
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oh is not a negative it's
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7 - 20 plus 20 so 7 plus 27 No 7 + -20
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would be what wait oh
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it's negative it's not a negative yes it
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is a negative yes it is 20 is a
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negative-3 my brain I'm telling you guys
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you have $7 how is it no but why would
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that be a negative okay it looks like a
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subtraction sign it's a subtraction
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right it's 7 minus 20 right you you have
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$7 and you spend 20 can you do that you
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have you short right I was 13
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$13 okay now what is -7 -
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107 -7 thank
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you
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-7 now this is the one that you all like
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right 12 -
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-6
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Nate 12
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--6 18 18 why because two have two
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negatives turn into what positive so
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that's 12 + 6 right that's 18 better -6
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actually no better call it -6
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-9 three three right because this is -6
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+ 9 because this two turn into a
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positive so you get pos3 all right so
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I'm glad you guys are getting it so
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let's continue we're going to do some
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more work
#Mathematics