- #1
Lily@pie
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Homework Statement
If a>0, then -a>0. Moreover, if a<b, then -a>-b
Homework Equations
axioms of real numbers can be applied
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