(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

If a>0, then -a>0. Moreover, if a<b, then -a>-b

2. Relevant equations

axioms of real numbers can be applied

3. The attempt at a solution

I am not sure what am I suppose to prove. So what I did was trying to prove "if a<b, then -a>-b" given that "If a>0, then -a>0."

I tried the direct proof method:

Suppose a<b, since we are given -a<a. So, -a<a<b. But I don't know how to bring -b in as the question didn't specify anything about b. So do I do 2 cases as in when b>0 and b<0?

I've also tried proof by contradiction:

Assuming a<b and -a<-b

But I don't know how to start ><

Need help!! Thanks sooo much

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# Homework Help: Proving order relation of real number

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