Timeline for Why is negative times negative = positive?
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| Sep 9, 2016 at 12:35 | comment | added | Leonardo Castro | I used up and down just to avoid all the assumptions about positive and negative, but they could be right and left, yin and yang, whatever... I wonder if yin times yin is yang or the other way around. | |
| Sep 9, 2016 at 12:33 | comment | added | Leonardo Castro | If you add an up and a down, you cancel out the amount they have in common keep the remaining up or down part. This would the subtraction of this algebra. Multiplying by $-1$ should be replaced by a simple inversion operator. Actually, $+1$ and $-1$ as multipliers are usually taken as the identity and inversion operators. In that way, they form a simple identity-inversion group and so $-1 \times -1 = 1$ since two inversions are equivalent to identity. I don't think, however, that algebra should necessarily be that way. | |
| Sep 9, 2016 at 12:22 | comment | added | Leonardo Castro | This $(-a)(-b)=ab$ stuff started when we gave up on distinguishing multiplier and multiplied in a multiplication. I can have three unities of apples, but I can't have apple unities of threes. In this sense, it's possible to have 3 unities of an 1D vector backwards $3 \times -1$ but not -1 unities of a vector forwards $-1 \times 3$, unless we define that a negative multiplier change the sense of the vector. I think a negative-free algebra can be created by distinguish three kind of numbers: scalar (no sign), up and down. | |
| Nov 20, 2014 at 0:19 | history | edited | Jack M | CC BY-SA 3.0 | deleted 148 characters in body |
| May 2, 2013 at 14:21 | history | edited | Jack M | CC BY-SA 3.0 | added 62 characters in body |
| May 2, 2013 at 14:07 | history | edited | Jack M | CC BY-SA 3.0 | added 29 characters in body |
| May 2, 2013 at 13:58 | history | edited | Jack M | CC BY-SA 3.0 | typos |
| May 2, 2013 at 13:49 | history | edited | Jack M | CC BY-SA 3.0 | added 4 characters in body |
| May 2, 2013 at 13:44 | history | answered | Jack M | CC BY-SA 3.0 |