问题
解答题
已知函数f(x)=m(x+
(1)求m的值; (2)若g(x)=f(x)+
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答案
(1)设P(x,y)是h(x)图象上一点,点P关于A(0,1)的对称点为Q(x0,y0),则x0=-x,y0=2-y.
∴2-y=m,∴y=m+2,从而m=
.1 4
(2)g(x)=
(x+1 4
)+1 x
=a 4x
(x+1 4
).a+1 x
设0<x1<x2≤2,
则g(x1)-g(x2)=
(x1+1 4
)-a+1 x1
(x2+1 4
)a+1 x2
=
(x1-x2)+1 4
(a+1)•1 4 x2-x1 x1x2
=
(x1-x2)•1 4
>0,x1x2-(a+1) x1x2
并且在x1,x2∈(0,2]上恒成立,
∴x1x2-(a+1)<0,
∴1+a>x1x2,1+a≥4,∴a≥3.