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a,b是正实数且a+b=1 证明:ab+1/ab〉=4+1/4
人气:387 ℃ 时间:2020-03-24 17:48:53
解答
ab+1/ab=ab+(a+b)/ab=ab+1/a+1/b
=ab+(a+b)/a+(a+b)b
=ab+2+a/b+b/a
>=ab+2+2
=ab+4
=a*(1-a)+4
那么设y=-a^2+a+4 (0
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