【y=1/x平方+根号x的值域怎么求?】-查字典问答网
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  【y=1/x平方+根号x的值域怎么求?】

  y=1/x平方+根号x的值域怎么求?

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2020-12-2622:12
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  y=1/(x^2)+x^(1/2)

  由于存在根号,所以x大于零

  y=1/(x^2)+(1/4)*x^(1/2))+(1/4)*x^(1/2))+(1/4)*x^(1/2))+(1/4)*x^(1/2)

  >=5*五次根号下(1/(x^2)*(1/4)*x^(1/2))*(1/4)*x^(1/2))*(1/4)*x^(1/2))*(1/4)*x^(1/2))

  =5*(2的负五分之八次方)

  当1/(x^2)=(1/4)*x^(1/2)时取等号,即x=2的负五分之四次方时有最小值5*(2的负五分之八次方),最大是正无穷大

2020-12-26 22:14:19
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