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I have a question concerning a proof that two negatives makes a positive :
One thing which I do not follow is, why the need to prove that -15 is really -15 ? We know that, (-5)+(-5)+(-5)=-15
Last edited by Al-Allo (2013-08-03 04:45:04)
Re: Proof question.
is by definition the additive inverse of , i.e. the unique integer such that .
To prove that an integer is equal to , add it to 15 and show that it equals zero.
Thus, to prove that , you need to show that . That is all the proof is doing. No other properties of are assumed.
Last edited by Nehushtan (2013-11-06 19:11:25)
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