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Current time:0:00Total duration:2:43

Topic A: Addition and subtraction of integers and rational numbers

Video transcript

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 so if we start at 0 and we are we move 1 2 3 4 spaces to the right of 0 this arrow right over here represents positive 4 we already see that right over here in the equation and then from positive 4 from the tip of this arrow we then go 1 2 3 4 5 6 spaces to the left so what we just did here is we just added a negative 6 to the positive 4 positive 4 plus negative 6 and 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 1 so 2 spaces to the left of 0 is going to be negative 2 this is fun let's keep doing more examples write an addition equation or subtraction equation your choice so they're giving us some choice to describe the diagram all right let's see was thinking what's going on here ok we're starting at 0 and we're going 1 2 3 4 to the left so if we're going 4 to the left or so we could say negative 4 negative 4 and then we and then we're going to go another 1 2 3 4 5 6 7 8 9 to the left so we could write this as negative 4 minus 9 is equal to and when you go 4 to the left and then you go another 9 to the left you end up 13 to the left of 0 which is negative 13 equals negative 13 so this way I've written it as a subtraction equation I guess you could say negative 4 minus 9 is equal to negative 13 now another way I could have done it I could have said negative 4 plus I could have said negative 4 plus negative 9 is equal to negative 13 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 and 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