1. induction model
(-5）×2=-10，（-5）×1=-5，（-5）×0=0.
thereby
(-5）×（-1）=5，（-5）×（-2）=10，（-5）×（-3）=15.
2. opposite number model
5×3=5+5+5=15，（-5）×3=（-5）+（-5）+（-5）=-15，
Therefore, a factor to replace his opposite number, the product obtained is the opposite of the original volume, it is (-5) × (-3) = 15.
3. Liabilities model
One debt 5 yuan per day, given date (0 RMB) 3 days 15 yuan debt. If the house referred to as 5-membered -5, then the "debt 5 yuan per day, three days debt" may be expressed mathematically: 3 × (-5) = - 15 The same person debt 5 yuan per day, then to. fixed date (0 yuan) three days ago, his property for more than 15 yuan more than the given date property. If we -3 indicates 3 days before using debt -5 indicates every day, then three days before his economy class is represented as (-3) × (-5) = 15.
4. Models story
Good (positive) or villains (negative), the city (a positive number) or out of town (negative), good (positive) and bad (negative).
If good (+) town (+), is a good thing for the town (+), the (+) × (+) = +
If good (+) out of town (-), for the town is bad (-), the (+) × (-) = -
If bad (-) town (+), is bad for the town (-), the (-) × (+) = -
If bad (-) out of town (-), is a good thing for the town (+), the (-) × (-) = +
If the model is not enough to make such a clever child Stendhal entirely convinced that this time, we can also use the following method to explain why the negatives make a positive.
（-5）×（-3）
=（-5）×（0-3）
=（-5）×0-（-5）×3
=0-（-15）
=15
The above is taken
https://baijiahao.baidu.com/s?id=1608740308584013160&wfr=spider&for=pc
That explained the significance about the burden 0 15 15 get the results,
Their understanding, A man, now in negative equity -100, one day he turned the money, earned 100, it can be said: assets and liabilities A cut off part of his income increased 2 assets.
Therefore, the current assets plus net income net assets = 100 + (- 100) = 0 0 = 100 obtained from the conversion equation - (-100).
That 0 - (- 100) = 100 how to explain the actual meaning of it. .
Scenario 1 If I have no money (0), on the road picked up $ 100, then that 0 + 100 = 100.
Scenario 2, treat it as someone else pay back the money:
you have 200 dollars
you borrowed $ 100 to your friends
that you have left 100 yuan
friends who owe you 100 yuan
recorded as -100
him pay you $ 100
on the math it will be subtracted owed
you is 200 yuan:
100-- (- 100) = 200 yuan
is the truth
is equivalent to a friend you the money
he does not owe you money
Baidu a moment, https://zhidao.baidu.com/question/438683078369982084.html
Meaning the number of burdens, temperature, altitude, in fact I think it is all one is defined. 0