1 |
2 |
(2)設(shè)x∈[0,1],則-x∈[-1,0],則f(?x)=
?x |
x2+1 |
因?yàn)楹瘮?shù)f(x)為偶函數(shù),所以有f(-x)=f(x)
既f(x)=
?x |
x2+1 |
所以f(x)=
|
(3)設(shè)0<x1<x2<1,則f(x2)?f(x1)=
?x2 |
x22+1 |
?x1 |
x12+1 |
(x2?x1)(x1x2?1) |
(x22+1)(x12+1) |
∵0<x1<x2<1
∴x2-x1>0,x1x2-1<0…(14分)
∴
(x2?x1)(x1x2?1) |
(1+ x12)(1+x22) |
∴f(x2)<f(x1)
∴f(x)在[0,1]為單調(diào)減函數(shù)…(16分)