김연성
When you multiply a negative number twice, why you get a positive number?
I'll explain it to you in an easy way.
-1+1=0.
It means that if you multiply any number x by A number that is the product of -1 and x, you get 0.
To generalize, if any number is x, x+(-1)*x=0.
Now define x as -1. (x = -1)
x=-1, and the equation is x+(-1)*x=0.
To add a number to -1 and get 0, you need to add 1.
x+(-1)*x=0 can be expressed as -1+(-1)*(-1)=0.
If you add any number to -1 to get 0, that number is 1. Since x=-1 before, this equation becomes (-1)*(-1)=(-1)*x=1.
-> (-1)*(-1)=1
So you learn that if you multiply a negative by a negative, you get a positive.
2024年11月21日 14:22
修正 · 2
When you multiply a negative number twice, why you get a positive number?
I'll explain it to you in an easy way.
-1+1=0.
It means that if you multiply any number x by A number that is the product of -1 and x, you get 0.
To generalize, if any number is x, x+(-1)*x=0.
Now define x as -1. (x = -1)
x=-1, and the equation is x+(-1)*x=0.
To add a number to -1 and get 0, you need to add 1.
x+(-1)*x=0 can be expressed as -1+(-1)*(-1)=0.
If you add any number to -1 to get 0, that number is 1. Since x=-1 before, this equation becomes (-1)*(-1)=(-1)*x=1.
-> (-1)*(-1)=1
So you learn that if you multiply a negative by a negative, you get a positive.
I am not convinced. You take for granted the existence of multiplication of integers. But how is it defined? What is meant by a*b if a and be are negative integers? Since you haven't said what it means, you can't come to any conclusion about it.
5 小時前
When you multiply a negative number twice, why DO you get a positive number? I'll
explain it to you in an easy way. -1+1=0. It means that if you multiply any
number x by A number that is the product of -1 and x, you get 0. To generalize,
if any number is x, x+(-1)*x=0. Now define x as -1. (x = -1) x=-1, and the
equation is x+(-1)*x=0. To add a number to -1 and get 0, you need to add 1.
x+(-1)*x=0 can be expressed as -1+(-1)*(-1)=0. If you add any number to -1 to
get 0, that number is 1. Since x=-1 before, this equation becomes
(-1)*(-1)=(-1)*x=1. -> (-1)*(-1)=1 So you learn that if you multiply a negative
by a negative, you get a positive.
6 小時前
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