Question 126351: why does a negative # times a negative # = a positve #
Answer by ilana(307)   (Show Source):
You can put this solution on YOUR website! That's a really good question! I would say it is because negative also means "the opposite of", so (-2)*(-3)=(-1)*(2)*(-1)*(3)=(-1)*(-1)*(2)*(3)=(The opposite of -1)*2*3=1*2*3=6. But like I said, that is a really good question to which I am sure there are better answers.
I just looked it up, in fact, and found that it is just accepted that (-1)(-1)=1.
You can also try proving it using the distributive property, as long as you are willing to assume (-1)(1)=-1.
(-1)(1+-1)=0 because (-1)(0)=0.
So distribute to get (-1)(1)+(-1)(-1)=0. So (-1)(1)=-(-1)(-1). So -1=-(-1)(-1). So 1=(-1)(-1), which you can use in my first explanation to prove it for any negative numbers.
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