设a>b>0 求a^2+1/(ab)+1/[a(a-b)]的最小值
人气:249 ℃ 时间:2020-03-29 23:44:02
解答
∵1/(ab)+1/[a(a-b)]=1/(ab)+1/(a^2-ab)=a^2/[ab(a^2-ab)]≥a^2*[2/(ab+a^2-ab)]^2=4/a^2当且仅当a=2b时,等号成立∴a^2+1/(ab)+1/[a(a-b)]≥a^2+4/a^2≥4当且仅当a=√2时,等号成立∴a^2+1/(ab)+1/[a(a-b)]的最小值为...
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