计算:(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)

来源:学生作业帮助网 编辑:作业帮 时间:2024/12/02 07:55:01
计算:(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)
xRJ0|I}A@^ {q^owWr

计算:(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)
计算:(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)
(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)

计算:(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)
1003/2005
平方差公式 分解 约分
(1-1/2^2)=(1-1/2)(1+1/2)=(1/2)*(3/2)
(1-1/3^2)=(1-1/3)(1+1/3)=(2/3)*(4/3)
.
(1-1/2005^2)=(1-1/2005)(1+1/2005)=(2004/2005)*(2006/2005)
所以 最后只有 (1/2)*(2006/2005)=1003/2005

1003/2005

:(1-1/2²)(1-1/3²)(1-1/4²)…(1-1/2004²)(1-1/2005²)
=(1+1/2)(1-1/2)(1+1/3)(1-1/3)....(1+1/2004)(1-1/2004)(1+1/2005)(1-1/2005)
=3/2*1/2*4/3*2/3...*2005/2004*2003/2004*2006/2005*2004/2005
=1/2*2006/2005
=1003/2005

1003/2005
平方差公式 分解 约分
(1-1/2^2)=(1-1/2)(1+1/2)=(1/2)*(3/2)
(1-1/3^2)=(1-1/3)(1+1/3)=(2/3)*(4/3)
....
(1-1/2005^2)=(1-1/2005)(1+1/2005)=(2004/2005)*(2006/2005)
所以 (1/2)*(2006/2005)=1003/2005