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Yeah, probably it is a stupid question If so sorry about that. But I wonder why left side is negative on number line and who had proofed that?

Anonim
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    It's just convention. The convention being this way rather than the other way sort of makes sense in societies that write left to right, since then the quantity on the horizontal axis increases as you move from left to right, which is the natural way to read graphs etc. for people from such societies. But from the math standpoint it could just as easily be the other way. – Ian Jul 16 '20 at 18:38
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    Are you serious? – Anonim Jul 16 '20 at 18:39
  • It has nothing to do with left or right. You just can put negatives in the right and do the math accordingly. –  Jul 16 '20 at 18:40
  • @Anonim Yes, why wouldn't they be? – Noah Schweber Jul 16 '20 at 18:40
  • Ah, If so I am too stupid that can't figure out it. – Anonim Jul 16 '20 at 18:40
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    It's a legitimate question, don't call yourself stupid. – scoopfaze Jul 16 '20 at 18:58
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    Yeah, this is a reasonable question, it just doesn't have a very interesting answer with a bunch of mathematical content to it. – Ian Jul 16 '20 at 18:59
  • Why do some countries drive on the left of the road and some on the right? A convention is required and, unfortunately, we don't all agree. In the case of the number line, the level of agreement is higher. For the vertical axis, variation is a bit more common. – badjohn Dec 28 '21 at 09:06

2 Answers2

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Copied from my comment:

It's just convention. The convention being this way rather than the other way sort of makes sense in societies that write left to right, since then the quantity on the horizontal axis increases as you move from left to right, which is the natural way to read graphs etc. for people from such societies. But from the math standpoint it could just as easily be the other way.

Ian
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We shall first begin with knowing what a negative number is on a number line. It was thought by the ancient Chinese civilizations that the left side (we now refer to with negative number was "evil"). Later on, they placed the positive number towards the right side as "good." However, in a mathematical context, as Ian wrote, it is because we read from the left from right (why do we do this?) because we have an instinct to mimic the way we write, which moves from the left to the right direction. This is why writers are taught to pay attention to words before commas or periods because that is where the reader's attention is focused. What if you were left-handed? You would write in a right to left direction; however, the number line would have the left side be equivalent to negative numbers. To understand this, we must only have a whole number on a number line: enter image description here; the right side is affiliated with the positive numbers. Perhaps, then, in your context, we should place the negative numbers on the right side of the number line. Indeed, we could do that, but it reveals to us that the negative numbers increase since it is x > 0. This would contradict the idea of having the negative sign before a negative value, i.e., ‘-1,’ which implies that it decreases. Hence, it must be that x < 0. So, in conclusion, the left side of a number line signifies that the numbers decrease, as with the case of negative numbers.

Akira
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