求函数f(x)=的反函数.

求函数f(x)=的反函数.

答案

解:当x≤-1时,y=x2+1≥2,且有x=-

,此时反函数为y=-(x≥2).

    当x>-1时,y=-x+1<2,且有x=-y+1,此时反函数为y=-x+1(x<2).

    ∴f(x)的反函数f-1(x)=

.

讲评:分段函数应在各自的条件下分别求反函数式及反函数的定义域,分段函数的反函数也是分段函数.


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