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Science,English,and math Ⅱ

No.38　17/05/02 10:57
燻し銀三 ( 50代 ♂ Oe38xe ) あ+あ-

【Expansion to a rational number】

《The concept of a number from the basic operation of arithmetic to a rational number》

ー2 × 3 ＝ー 6,it means that minus 2 is added three times so it's easy to understand for even me,but ー 2 × ー 3 ＝ 6…why? I'm going to think why it is.

Intuition tells me that minus is opposite of plus. One minus number multiply by other minus number means that opposition of the opposition,so it returns as it is,so it's plus. To tell the truth I can't understand it any more,but the book expresses like the next.

The distributive law stands up to the plus number. Considering that the distributive law stands up to the whole rational number,minus number multiple by multiple minus number becomes a plus number is indicated. By the way what is the distritbutive law?

It's the equation that a（b+c）＝ab + ac. Then there are next two equations,the one is a×0＝0,and and let's suppose the a was ー2,and other equation is 0 = 3ー3. It means that ー2 × 0 ＝3 ー3… I find it tedious…