11.éCï¼12.æ大å¼ä¸º(1/16); 13.æ大å¼ä¸º5ï¼ 14.æå°å¼ä¸º2â2;
15.æå°å¼ä¸º3/4ï¼ 16.æ大å¼ä¸º9/8;
17.(1).âµa+b=1ï¼â´1/a+1/b=(1/a+1/b)(a+b)=1+b/a+a/b+1=2+b/a+a/b>2+2=4
(2).è¥a+b+c=1,(aãbãcâR+)ï¼å1/a+1/b+1/c=(1/a+1/b+1/c)(a+b+c)
=1+b/a+c/a+a/b+1+c/b+a/c+b/c+1
=3+b/a+c/a+a/b+c/b+a/c+b/c>3+6=9.
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