q5备胎低音炮:数学难题!!!

来源:百度文库 编辑:杭州交通信息网 时间:2024/05/05 12:32:02
计算:(1- 1/2^2 )(1- 1/3^2 )(1- 1/4^2 )……(1- 1/10^2 )
请写明解题步骤

原式=(1-1/2)(1+1/2)(1-1/3)(1+1/3)...(1-1/10)(1+1/10)
=(1/2)*(3/2)*(2/3)*(4/3)*(3/4)*...*(9/10)*(11/10)
=(1/2)*(11/10)
=11/20

1- 1/2^2 =1/2*3/2
1- 1/3^2 =2/3*4/3
1- 1/4^2 =3/4*5/4
....
1- 1/10^2=9/10*11/10
将上面各式相乘得:
(1- 1/2^2 )(1- 1/3^2 )(1- 1/4^2 )……(1- 1/10^2 )
=1/10*11/2
=11/20