填空题已知函数f(x)=x2-cosx,则f(-0.5),f(0),f(0.6)的由大

发布时间:2020-07-09 09:05:24

填空题已知函数f(x)=x2-cosx,则f(-0.5),f(0),f(0.6)的由大到小关系为________.

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f(0.6)>f(-0.5)>f(0)解析分析:由f(x)=x2-cosx为偶函数,知f(-0.5)=f(0.5),由f(x)在(0,1)为增函数,知f(0)<f(0.5)<f(0.6),由此能比较f(-0.5),f(0),f(0.6)的大小关系.解答:∵f(x)=x2-cosx为偶函数,∴f(-0.5)=f(0.5),∵f′(x)=2x+sinx,由x∈(0,1)时,f′(x)>0,知f(x)在(0,1)为增函数,所以f(0)<f(0.5)<f(0.6)所以f(0)<f(-0.5)<f(0.6),即f(0.6)>f(-0.5)>f(0).故
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