已知函数f(x)=ax-1ax+1(a>0,且a≠1),设函数g(x)=f(x-12)+1(Ⅰ)求证:f(x)是奇函数;(Ⅱ)①求证:g(x)+g(1-x)=2;②求g(0)+g(1100)+g(21

题目简介

已知函数f(x)=ax-1ax+1(a>0,且a≠1),设函数g(x)=f(x-12)+1(Ⅰ)求证:f(x)是奇函数;(Ⅱ)①求证:g(x)+g(1-x)=2;②求g(0)+g(1100)+g(21

题目详情

已知函数f(x)=
ax-1
ax+1
(a>0,且a≠1),设函数g(x)=f(x-
1
2
)+1

(Ⅰ)求证:f(x)是奇函数;
(Ⅱ)①求证:g(x)+g(1-x)=2;②求g(0)+g(
1
100
)+g(
2
100
)+…+g(
99
100
)+g(1)
的值.
题型:解答题难度:中档来源:不详

答案

证明:(I)f(x)定义域为R,f(-x)=
a-x-1
a-x+1
=
1-ax
1+ax
=-f(x)

所以f(x)为奇函数,----------(5分)
(Ⅱ)①g(x)+g(1-x)=f(x-class="stub"1
2
)+1+f(class="stub"1
2
-x)+1
=f(x-class="stub"1
2
)+f(class="stub"1
2
-x)+2

因为f(x)为奇函数,所以 f(x-class="stub"1
2
)+f(class="stub"1
2
-x)=0

所以g(x)+g(1-x)=2.--------------(10分)
②由①知g(x)+g(1-x)=2,
所以g(0)+…+g(1)=[g(0)+g(1)]+[g(class="stub"1
100
+gclass="stub"99
100
)]+…+[g(class="stub"49
100
)+g(class="stub"51
100
)]
+g(class="stub"1
2
)=2×50+1=101
--------------------(15分)

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