设f(x)=4x4x+2,求f(1/1001)+f(2/1001)+f(3/1001)+…+f(1000/1001)的值.

问题描述:

f(x)=

4x
4x+2
,求f(
1
1001
)+f(
2
1001
)+f(
3
1001
)+…+f(
1000
1001
)的值.

f(1-x)=

41−x
41−x+2
=
4
4+2•4x
=
2
2+4x

∴f(x)+f(1-x)=
4x
4x+2
+
2
2+4x
=1,
f(
1
1001
)+f(
1000
1001
)=f(
2
1001
)+f(
999
1001
)=…
=f(
500
1001
)=f(
501
1001
)=1,
f(
1
1001
)+f(
2
1001
)+f(
3
1001
)+…+f(
1000
1001
)=500