Let A subset or equal of R be bounded above and let c belong to R.Define the sets c+A and cA by c+A={c+a : a belong to A} and cA={ca : a belong to A}.
1-show that sup(c+A)=c+ Sup A
2-if c>=0,show that sup(cA)=cSupA
3-postulate a similar type of statement for sup(cA)for the case c